Interchangeable lens device, imaging device, imaging system, method, and program

ABSTRACT

Provided are a device and a method by which high-precision auto focus (AF) processing can be performed while a focus lens or a zoom lens is being operated. An interchangeable lens acquires position information regarding a focus lens and a zoom lens at a predetermined time interval during an exposure time period of detection information acquisition pixels for use in calculation of a defocus amount (DF), and outputs the position information to an imaging device. The imaging device calculates the defocus amount (DF) by using information regarding the detection information acquisition pixels, calculates a reference focus lens position (Ref_fc) by using points, on a cam curve, corresponding to the inputted lens position information, calculates a target focus lens position (Tgt_fc) in an in-focus position, from the reference focus lens position (Ref_fc) and the defocus amount (DF), and outputs the target focus lens position (Tgt_fc) to the interchangeable lens.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation application of U.S. patentapplication Ser. No. 16/625,970, filed Dec. 23, 2019, which is a 371Nationalization of PCT/JP2018/016829, filed Apr. 25, 2018, and claimsthe benefit of Japanese Priority Patent Application JP 2017-124826 filedon Jun. 27, 2017, the entire contents of which are incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates to an interchangeable lens device, animaging device, an imaging system, a method, and a program, andparticularly, relates to an interchangeable lens device, an imagingdevice, an imaging system, a method, and a program for performing autofocus (AF) processing.

BACKGROUND ART

In a case where image photographing using a camera (imaging device) iscarried out, focus adjustment (focusing point adjustment) which is aprocess for focusing on a subject is necessary.

Most existing cameras have auto focus (AF) functions for automaticallyperforming such focus adjustment.

There are some methods for implementing an AF function. These methodsinclude, for example, the following methods:

a contrast detection method involving acquiring photographed images at aplurality of focus lens set positions, and setting, as a focus position(in-focus position), a position at which the photographed image havingthe highest contrast has been acquired; and

a phase difference detection method involving generating a pair ofimages by pupil-splitting light having passed through an imaging lens,and analyzing the phase difference between the generated pair of images,thereby detecting a focus position (in-focus position).

These methods have been known.

Note that, for example, PTL 1 (Japanese Patent Laid-open No.2014-137468), etc. describes a process for detecting a focus position(in-focus position) by the phase difference detection method.

In order to achieve high-speed auto focusing (AF), a focus position(in-focus position) needs to be decided with a focus lens being driven.

However, in each of the contrast detection and the phase differencedetection, when the above processing is performed, at which focus lensposition the contrast detection information or phase differencedetection information is obtained is unclear. Thus, there is a problemthat high-precision auto focusing (AF) is difficult.

Moreover, when a user (photographing person) carries out zoom adjustmentto drive a zoom lens during execution of auto focus (AF) processing, thefocus position is changed. Thus, there is a problem that high-precisionauto focusing (AF) cannot be performed.

Note that PTL 2 (Japanese Patent Laid-open No. 2017-37103) discloses aconfiguration of controlling the position of a focus lens while takingthe correspondence between a zoom position and the position of the focuslens position into consideration.

However, in the configuration disclosed in PTL 2, the output reliabilityof focusing point detecting means is determined, and, in the case wherethe reliability is low, position control of the focus lens is performedagain by a different method. Thus, this configuration has a problem thatthe adjustment requires much time. This configuration cannot be used ina case where high-speed auto focusing (AF) is requested such as inconsecutive shooting, for example.

CITATION LIST Patent Literature [PTL 1]

Japanese Patent Laid-open No. 2014-137468

[PTL 2]

Japanese Patent Laid-open No. 2017-037103

SUMMARY Technical Problem

The present disclosure has been made in view of the aforementionedproblems, for example, and an object thereof is to provide aninterchangeable lens device, an imaging device, an imaging system, amethod, and a program by which high-precision auto focus (AF) processingcan be performed while a focus lens or a zoom lens is moving.

Solution to Problem

A first aspect of the present disclosure is an interchangeable lensdevice including

a memory that stores a cam curve representing a relationship between aposition of a zoom lens and a position of a focus lens according to asubject distance, and

a control section that performs focus control by driving the focus lens.

The control section

-   -   transmits zoom lens position information indicating the position        of the zoom lens and focus lens position information indicating        the position of the focus lens to an imaging device, and    -   performs the focus control on the basis of subject distance        information indicating a substance distance which is calculated        by the imaging device with use of the zoom lens position        information and the focus lens position information acquired        from the control section, and on the basis of the cam curve.

Furthermore, a second aspect of the present disclosure is an imagingdevice including

a memory that stores a cam curve representing a relationship between aposition of a zoom lens and a position of a focus lens according to asubject distance, and

a focus control section that calculates an in-focus position of thefocus lens.

The focus control section

-   -   receives an input of pixel information regarding a detection        information acquisition pixel, and calculates a defocus amount,    -   receives, from a connected interchangeable lens device, an input        of multiple sets of lens position information regarding the        focus lens and the zoom lens acquired at a predetermined time        interval during an exposure time period of the detection        information acquisition pixel,    -   detects points, on the cam curve, corresponding to the multiple        sets of lens position information, and calculates a reference        focus lens position by using the detected corresponding points        on the cam curve, and    -   calculates subject distance information indicating a subject        distance, by using the calculated reference focus lens position        and the defocus amount.

Furthermore, a third aspect of the present disclosure is an imagingsystem including an interchangeable lens and an imaging device.

The interchangeable lens

-   -   acquires lens position information regarding a focus lens and a        zoom lens at a predetermined time interval during an exposure        time period of a detection information acquisition pixel for use        in calculation of a defocus amount, and outputs the lens        position information to the imaging device, and

the imaging device

-   -   receives an input of pixel information regarding the detection        information acquisition pixel, and calculates a defocus amount,    -   calculates a reference focus lens position by using the lens        position information inputted from the interchangeable lens, and    -   calculates subject distance information indicating a subject        distance, by using the calculated reference focus lens position        and the defocus amount, and outputs the subject distance        information to the interchangeable lens.

Furthermore, a fourth aspect of the present disclosure is a focuscontrol method which is executed by an interchangeable lens device.

The interchangeable lens includes

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a control section that performs focus control by driving the        focus lens.

The method includes, by means of the control section,

-   -   transmitting zoom lens position information indicating the        position of the zoom lens and focus lens position information        indicating the position of the focus lens to an imaging device,        and    -   performing the focus control on the basis of subject distance        information indicating a subject distance which is calculated by        the imaging device with use of the zoom lens position        information and the focus lens position information acquired        from the control section, and on the basis of the cam curve.

Furthermore, a fifth aspect of the present disclosure is a focus controlmethod which is executed by an imaging device.

The imaging device includes

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a focus control section that calculates an in-focus position of        the focus lens.

The method includes, by means of the focus control section,

-   -   receiving an input of pixel information regarding a detection        information acquisition pixel, and calculating a defocus amount,    -   receiving, from a connected interchangeable lens device, an        input of multiple sets of lens position information regarding        the focus lens and the zoom lens acquired at a predetermined        time interval during an exposure time period of the detection        information acquisition pixel,    -   detecting points, on the cam curve, corresponding to the        multiple sets of lens position information, and calculating a        reference focus lens position by using the detected        corresponding points on the cam curve, and    -   calculating subject distance information indicating a subject        distance by using the calculated reference focus lens position        and the defocus amount.

Furthermore, a sixth aspect of the present disclosure is a program forcausing an interchangeable lens device to perform focus controlprocessing.

The interchangeable lens includes

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a control section that performs focus control by driving the        focus lens.

The program is for causing the control section to

-   -   transmit zoom lens position information indicating the position        of the zoom lens and focus lens position information indicating        the position of the focus lens to an imaging device, and    -   perform the focus control on the basis of subject distance        information indicating a subject distance which is calculated by        the imaging device with use of the zoom lens position        information and the focus lens position information acquired        from the control section, and on the basis of the cam curve.

Furthermore, a seventh aspect of the present disclosure is a program forcausing an imaging device to perform focus control processing.

The imaging device includes

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a focus control section that calculates an in-focus position of        the focus lens.

The program is for causing the focus control section to execute

-   -   reception of an input of pixel information regarding a detection        information acquisition pixel, and calculation of a defocus        amount,    -   reception, from a connected interchangeable lens device, of an        input of multiple sets of lens position information regarding        the focus lens and the zoom lens acquired at a predetermined        time interval during an exposure time period of the detection        information acquisition pixel,    -   detection of points, on the cam curve, corresponding to the        multiple sets of lens position information, and calculation of a        reference focus lens position by using the detected        corresponding points on the cam curve, and    -   calculation of subject distance information indicating a subject        distance by using the calculated reference focus lens position        and the defocus amount.

Note that a program according to the present disclosure can be providedby a recording medium or a communication medium for providing theprogram in a computer readable format to an information processingdevice or a computer system that is capable of executing various programcodes, for example. Since such program is provided in a computerreadable format, processing in accordance with the program is executedon the information processing device or the computer system.

Other objects, features, and advantages of the present disclosure willbecome apparent from the more detailed description based on theembodiments and the attached drawings of the present disclosure whichare described later. Note that, in the present description, a systemrefers to a logical set structure including a plurality of devices, andthe devices of the structure are not necessarily included in the samecasing.

Advantageous Effect of Invention

With the configuration of one embodiment according to the presentdisclosure, a device and a method by which high-precision auto focus(AF) processing can be performed while a focus lens or a zoom lens isbeing operated, are implemented.

Specifically, for example, an interchangeable lens acquires positioninformation regarding a focus lens and a zoom lens at a predeterminedtime interval during an exposure time period of a detection informationacquisition pixel for use in calculation of a defocus amount (DF), andoutputs the position information to an imaging device. The imagingdevice calculates a defocus amount (DF) by using the detectioninformation acquisition pixel information, calculates a reference focuslens position (Ref_fc) by using points, on a cam curve, corresponding tothe inputted lens position information, calculates a target focus lensposition (Tgt_fc) in an in-focus position from the reference focus lensposition (Ref_fc) and the defocus amount (DF), and outputs the targetfocus lens position (Tgt_fc) to the interchangeable lens.

With this configuration, a device and a method by which high-precisionauto focus (AF) processing can be performed while a focus lens or a zoomlens is being operated, are implemented.

Note that the effects described in the present description are mereexamples, and thus, are not limited. In addition, another effect may beprovided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram of a configuration example of animaging system.

FIG. 2 is an explanatory diagram of a configuration example of aninterchangeable lens and an imaging device (body) constituting theimaging system.

FIG. 3 is an explanatory diagram of an example of a pixel configurationin an imaging element having phase difference detection pixels.

FIG. 4 is an explanatory diagram of an example of an imaging sequence.

FIG. 5 is an explanatory diagram of an example of calculation of adefocus amount.

FIG. 6 is an explanatory diagram of an example of calculation of adefocus amount.

FIG. 7 is an explanatory diagram of an example of calculation of adefocus amount and calculation of a target focus lens position.

FIG. 8 is an explanatory diagram of a cam curve.

FIG. 9 is an explanatory diagram of an example of storing cam curve datain the imaging system according to the present disclosure.

FIG. 10 is an explanatory diagram of one example of a data processingsequence in the imaging system according to the present disclosure.

FIG. 11 is an explanatory diagram of acquisition and transmission oflens position information which are executed by the imaging systemaccording to the present disclosure.

FIG. 12 is an explanatory diagram of an example of lens positioninformation data which is used in the imaging system according to thepresent disclosure.

FIG. 13 is an explanatory diagram of calculation of a defocus amount,which is executed by the imaging system according to the presentdisclosure.

FIG. 14 is an explanatory diagram of calculation of a target focus lensposition, which is executed by the imaging system according to thepresent disclosure.

FIG. 15 is an explanatory diagram of calculation of a target focus lensposition, which is executed by the imaging system according to thepresent disclosure.

FIG. 16 is an explanatory diagram of calculation of a target focus lensposition, which is executed by the imaging system according to thepresent disclosure.

FIG. 17 is an explanatory diagram of calculation of a target focus lensposition, which is executed by the imaging system according to thepresent disclosure.

FIG. 18 is an explanatory diagram of transmission of a target focus lensposition, which is executed by the imaging system according to thepresent disclosure.

FIG. 19 is an explanatory diagram of focus lens driving, which isexecuted by the imaging system according to the present disclosure.

FIG. 20 is an explanatory diagram of focus lens driving, which isexecuted by the imaging system according to the present disclosure.

FIG. 21 is a sequence diagram for explaining a process sequence which isexecuted by the imaging system according to the present disclosure.

FIG. 22 is a sequence diagram for explaining a process sequence which isexecuted by the imaging system according to the present disclosure.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an interchangeable lens device, an imaging device, animaging system, a method, and a program according to the presentdisclosure will be explained in detail with reference to the drawings.Note that explanations will be given in accordance with the followingitems.

1. Configuration Example of Interchangeable Lens Device, Imaging Device,and Imaging System

2. Specific Sequence Example of Auto Focus (AF) Processing

3. Problems Caused When AF Processing Is Performed with Focus Lens BeingDriven

4. Auto Focus (AF) Processing in Which Zoom Position Is Taken intoConsideration

5. Data Communication between Interchangeable Lens and Imaging Device(Body) and Process Sequence Thereof

6. Conclusion of Configuration According to Present Disclosure

1. Configuration Example of Interchangeable Lens Device, Imaging Device,and Imaging System

First, a configuration example of the interchangeable lens device, theimaging device, and the imaging system will be explained with referenceto FIG. 1 and later.

FIG. 1 is a diagram depicting one example of an imaging system 1.

The imaging system 1 includes an interchangeable lens 2 and an imagingdevice (body) 5.

The interchangeable lens 2 is a lens unit that can be attached to anddetached from the imaging device (body) 5.

The interchangeable lens 2 incorporates various lenses including a focuslens and a zoom lens, further includes a driving section that drives thelenses and a control section that outputs a driving signal to thedriving section, and further includes a mount section having acommunication function and a connection function with respect to theimaging device (body) 5, and the like.

A specific configuration example of the interchangeable lens 2 will beexplained later with reference to FIG. 2 .

The imaging device (body) 5 includes an imaging element 6 thatphotographs a subject image incident via the interchangeable lens 2, adisplay section 7 that displays the image photographed by the imagingelement 6, an operation section (shutter button) 8 for starting aphotographing process, and the like.

Although not illustrated in the figure, a recording section that storesan image photographed by the imaging element 6, a signal processingsection that performs image processing on the image photographed by theimaging element 6, a mount section that has a communication function anda connection function with respect to the interchangeable lens 2, andthe like are included.

A specific configuration example of an imaging system including animaging device and an interchangeable lens will be explained withreference to FIG. 2 .

An imaging system 10 depicted in FIG. 2 includes an interchangeable lens20 and an imaging device (body) 50. The imaging system 10, theinterchangeable lens 20, and the imaging device (body) 50 correspond tothe imaging system 1, the interchangeable lens 2, and the imaging device(body) 5 depicted in FIG. 1 , respectively.

The imaging system 10 in FIG. 2 is a lens interchangeable type digitalcamera, and includes the interchangeable lens 20 that can be attachedthereto and detached therefrom, and the imaging device (body) 50 servingas a camera main body side.

The interchangeable lens 20 includes a mount section 21 that isdetachably attached to a mount section 61 of the imaging device (body)50. The mount section 21 includes a plurality of terminals that iselectrically connected to the imaging device (body) 50, and acommunication section that communicates with the imaging device (body)50.

Further, the interchangeable lens 20 includes a lens-side controlsection 22, a zoom lens 23, a hand shake correction lens 24, an aperture25, a focus lens 26, an operation section 41, a memory 42, and a powersupply control section 43.

Further, the interchangeable lens 20 includes a zoom lens drivingsection 31, a hand shake control section 32, an aperture control section33, a focus lens driving section 34, and a lens position (state)detection section 27.

The lens-side control section 22 includes, for example, a computationprocessing unit such as a CPU (Central Processing Unit) or an MPU (MicroProcessing Unit) and a peripheral circuit thereof, and controls theentire interchangeable lens 20 by reading out a predetermined controlprogram stored in the memory 42 and executing the program.

Note that the lens-side control section 22 has a clock for measuringtime information, and outputs synchronization signals to the processingsections, and thereby controls respective processing timings at theprocessing sections.

For example, the lens-side control section 22 controls the position ofthe zoom lens 23 in accordance with a command supplied from the imagingdevice (body) 50 via a predetermined communication terminal of the mountsection 21 or a user's operation received through the operation section41.

Specifically, the lens-side control section 22 acquires the currentposition of the zoom lens 23 from the lens position (state) detectionsection 27, which includes a magnetic sensor (MR sensor) or the like,for example, decides a driving direction and a driving amount for movingthe zoom lens 23 to a predetermined position on the basis of theacquisition result, and outputs the decided driving direction anddriving amount together with a movement command to the zoom lens drivingsection 31. On the basis of the movement command supplied from thelens-side control section 22, the zoom lens driving section 31 moves thezoom lens 23 in an optical axis direction so as to achieve the commandeddriving direction and driving amount.

Moreover, the lens-side control section 22 controls the hand shakecorrection lens 24 to correct hand shakes. Specifically, the lens-sidecontrol section 22 decides, in a direction for canceling a hand shakeamount, a driving direction and a driving amount for the hand shakecorrection lens 24 on the basis of the hand shake amount detected by ahand shake detection sensor incorporated in the lens position (state)detection section 27, and outputs the decided driving direction anddriving amount together with a movement command to the hand shakecontrol section 32. The hand shake detection sensor includes a gyrosensor and/or a triaxial acceleration sensor, for example. The gyrosensor is used to detect a deviation (shake) in a directioncorresponding to Pitch or Yaw as the correction direction of the handshake correction lens 24. The triaxial acceleration sensor is used todetect deviations (shakes) in directions which are defined as an X-axisand a Y-axis when the optical axis direction is defined as a Z-axis. Onthe basis of the movement command supplied from the lens-side controlsection 22, the hand shake control section 32 moves the hand shakecorrection lens 24 so as to achieve the commanded driving direction anddriving amount.

The lens-side control section 22 performs control to mechanically lockthe hand shake correction lens 24 in a case where power supply is turnedoff. In other words, in a state where power is being supplied from theimaging device (body) 50 to the interchangeable lens 20, the hand shakecorrection lens 24 is kept at a predetermined position under the controlby the hand shake control section 32, but when the power supply isturned off, the position control by the hand shake control section 32 isstopped so that the hand shake correction lens 24 moves downward in agravity direction by a predetermined amount. According to timing atwhich the power supply is turned off, the lens-side control section 22prevents downward movement of the hand shake correction lens 24 bymechanical locking of the hand shake correction lens 24 via the handshake control section 32. The hand shake control section 32 mechanicallylocks the hand shake correction lens 24 on the basis of a fixationcommand supplied from the lens-side control section 22.

The lens-side control section 22 controls (the aperture diameter of) theaperture 25 in accordance with a command, etc., supplied from theimaging device (body) 50 via a predetermined communication terminal ofthe mount section 21. Specifically, the lens-side control section 22acquires an aperture diameter of the aperture 25 detected by an aperturedetection sensor (not illustrated), and instructs the aperture controlsection 33 to obtain an F value according to the command from theimaging device (body) 50 such that the aperture 25 is driven. Theaperture control section 33 drives the aperture 25 to have the aperturediameter according to a command from the lens-side control section 22.

Further, the lens-side control section 22 controls the focus lens 26.Specifically, the lens-side control section 22 acquires the currentposition of the focus lens 26 from the lens position (state) detectionsection 27, decides a driving direction and a driving amount for movingthe focus lens 26 to a predetermined position on the basis of theacquisition result, and outputs the decided driving direction anddriving amount together with a movement command to the focus lensdriving section 34. The focus lens driving section 34 moves the focuslens 26 in the optical axis direction such that the driving directionand the driving amount according to the command are obtained. The focuslens 26 includes one or more optical elements. Note that the focus lens26 may be configured by two focus lens groups: a focus lens group on aside close to the zoom lens 23; and a focus lens group on a side closeto an imaging element 65 of the imaging device (body) 50.

The lens position (state) detection section 27 can include, for example,a magnetic sensor, a photodiode array, a potentiometer, areflection-type optical encoder, or the like.

The focus lens driving section 34 can include, for example, anultrasonic motor, a DC motor, a linear actuator, a stepping motor, apiezo element (piezoelectric element), or the like.

The lens-side control section 22 performs various types of control inaccordance with a command supplied from the imaging device (body) 50 viaa predetermined communication terminal of the mount section 21 or auser's operation received through the operation section 41.

The operation section 41 corresponds to a zoom ring for manually settinga zooming magnification, a focus ring for manually setting a focus lens,or the like, receives a user's manual operation, and supplies anoperation signal corresponding to the received operation to thelens-side control section 22.

The memory 42 is a storage section including a RAM (Random AccessMemory), a ROM (Read Only Memory), or the like, for example, and storesvarious types of data such as a control program, storage regions ofvarious types of data being operated, a predetermined control programwhich is executed by the lens-side control section 22, and adjustmentparameters.

The power supply control section 43 detects the power amount of powersupplied from the imaging device (body) 50, and supplies power to thesections (lens-side control section 22 and various driving sections) ofthe interchangeable lens 20 by respective optimally allocated poweramounts on the basis of the detected power amount.

On the other hand, the imaging device (body) 50 serving as a body sideincludes the mount section 61 to which the interchangeable lens 20 isdetachably attached. The mount section 61 includes a plurality ofterminals that is electrically connected to the mount section 21 of theinterchangeable lens 20, and a communication section that communicateswith the interchangeable lens 20.

When the interchangeable lens 20 is attached to the mount section 61 ofthe imaging device (body) 50, the terminals of the mount section 61 areelectrically and physically connected to corresponding terminals of themount section 21 of the interchangeable lens 20. The terminals forconnection include a terminal for power supply (a power supplyterminal), a terminal for transmitting commands or data (a communicationterminal), a terminal for transmitting synchronization signals (asynchronization signal terminal), and the like, for example.

The imaging device (body) 50 further includes a body-side controlsection 62, a shutter 63, a shutter control section 64, the imagingelement 65, an AD conversion section 66, a frame memory 67, an imagesignal processing section 68, a recording section 69, a recording medium70, a display section 71, a memory 72, a power supply section 75, apower supply control section 76, an operation section 78, and a focuscontrol section 80.

The body-side control section 62 includes, for example, a computationprocessing unit such as a CPU (Central Processing Unit) or an MPU (MicroProcessing Unit) and a peripheral circuit thereof, etc., and reads outand executes a predetermined control program recorded in the memory 72,and thereby controls a process which is executed by the imaging device(body) 50 and overall processes in the imaging system 10.

Note that the body-side control section 62 includes a clock formeasuring time information, and outputs synchronization signals to theprocessing sections, for example, and thereby controls the timings ofprocesses which are executed at the respective processing sections.

The memory 72 is a storage section including a RAM (Random AccessMemory), a ROM (Read Only Memory), or the like, for example, and storesvarious types of data such as a control program, storage regions ofvarious types of data being operated, a predetermined control programwhich is executed by the body-side control section 62, and adjustmentparameters.

For example, the body-side control section 62 causes the imaging element65 to execute imaging on the basis of an operation signal indicating apredetermined user's operation supplied from the operation section 78.Further, the body-side control section 62 drives the focus lens 26 andthe zoom lens 23, etc., by transmitting a predetermined command to theinterchangeable lens 20 via the mount section 61.

In addition, for example, lens position information regarding the focuslens 26 and zoom position information regarding the zoom lens 23, etc.are supplied from the interchangeable lens 20 to the body-side controlsection 62 via the mount section 61 so that, at an optimum timing basedon the information, the body-side control section 62 causes the imagingelement 65 to capture an image that is to be recorded in the recordingsection 69 or capture an image that is to be transmitted to an externaldevice. The (data of) image obtained by the imaging element 65 isrecorded (stored) in the recording medium 70 via the recording section69 under control by the body-side control section 62, and is furtherdisplayed on the display section 71.

The shutter 63 is disposed on a front surface of the imaging element 65,and is opened and closed under control by the shutter control section64. When the shutter 63 is in a closed state, light of a subject havingpassed through the optical system of the interchangeable lens 20 isblocked. The shutter control section 64 detects the open/closed state ofthe shutter 63, and supplies the state to the body-side control section62. The shutter control section 64 drives the shutter 63 to an openstate or a closed state under control by the body-side control section62.

The imaging element 65 includes a CCD (Charge Coupled Device) or a CMOS(Complementary Mental Oxide Semiconductor) sensor, for example,generates image data by imaging a subject, and outputs the image data.

In a case where the imaging element 65 includes a CCD sensor or a CMOSsensor, an electric shutter can be used. Accordingly, the shutter 63 maybe omitted. In a case where the shutter 63 is omitted, the shuttercontrol section 64, which is used for controlling the shutter 63, isalso omitted.

Note that the imaging element 65 includes image photographing pixels(RGB pixels), and detection information acquisition pixels which areused for auto focus processing, i.e., phase difference detection pixelsfor acquiring phase difference information.

A specific example of the pixel configuration in the imaging element 65will be explained with reference to FIG. 3 .

FIG. 3 is a diagram depicting an example of the pixel configuration inthe imaging element 65. The Y-axis represents the up-down direction, andthe X-axis represents the left-right direction. In FIG. 3 , each squarerepresents one pixel.

RGB pixels depicted in FIG. 3 are normal image photographing pixels. TheRGB pixels have a Bayer array configuration, for example.

Detection information acquisition pixels which are used for auto focusprocessing, i.e., phase difference detection pixels 81 for acquiringphase difference information, are discretely set in portions (lines) ofthe RGB pixels having the Bayer array.

The phase difference detection pixels include pairs each including aright aperture phase difference detection pixel Pa and a left aperturephase difference detection pixel Pb.

The imaging element 65 separately performs the following two data outputprocesses:

(1) output of pixel information (image signal) by pixels (RGB pixels)for photographed images; and

(2) output of phase difference detection pixel information ((AF)detection signal) by the phase difference detection pixels 81.

The “(1) output of pixel information (image signal) by pixels (RGBpixels) for photographed images” is made in accordance with an imagephotographing timing given by a user (photographing person). Further, adisplay image (live-view image) to be displayed on the display section71 is outputted even during a non-photographing time. The display image(live-view image) is outputted at a frame rate corresponding to theimage display rate of the display section 71.

The “(2) output of phase difference detection pixel information(detection signal) by the phase difference detection pixels 81” is madeat an interval shorter than an image outputting interval, or at a (1/60)-sec (=16.7 msec) interval, for example.

As depicted in FIG. 2 , output from the imaging element 65 is inputtedto the AD conversion section 66, and is converted to a digital signal.

The “(1) output of pixel information (image signal) by pixels (RGBpixels) for photographed images” is inputted to the AD conversionsection 66, is converted to a digital signal, is stored in the framememory 67, and is then inputted to the image signal processing section68.

The image signal processing section 68 performs, for example, generalcamera signal processing such as white balance (WB) adjustment and gammacorrection, and thereby generates an output image, that is, an image tobe displayed on the display section 71 or an image to be recorded in therecording medium 70.

In FIG. 2 , this data stream is indicated by a stream 1 (St1).

On the other hand, the “(2) output of phase difference detection pixelinformation (detection signal) by the phase difference detection pixels81” is inputted to the AD conversion section 66, is converted to adigital signal, and is then inputted to the focus control section 80.

The focus control section 80 analyzes the phase difference between apair of images generated from the phase difference detection pixelinformation (detection signal), and thereby calculates a focus deviationamount to a subject (focus target) which is a target to be focused, thatis, the deviation amount (defocus amount (DF)) between the in-focusdistance and the subject distance.

In FIG. 2 , a data stream corresponding to the “(2) output of phasedifference detection pixel information (detection signal) by the phasedifference detection pixels 81” is indicated by a stream 2 (St2).

In this manner, the two data streams are outputted from the imagingelement 65.

These two streams are outputted at separate timings independent of eachother.

An example of a detailed output sequence of the two data sets will beexplained later.

The image signal processing section 68 performs predetermined imagesignal processing on an image supplied from the imaging element 65. Forexample, the image signal processing section 68 converts a RAW imagesupplied from the imaging element 65 into image data in a predeterminedfile format, and records the image data in the recording medium 70 viathe recording section 69. In addition, the image signal processingsection 68 performs demosaic processing on the RAW image, and further,performs reversible compression or irreversible compression thereon toconvert the image to image data in a predetermined file format, andrecords the image data in the recording medium 70 via the recordingsection 69. Moreover, for example, the image signal processing section68 converts the image data supplied from the imaging element 65, to animage signal in a predetermined display format, and supplies the imagesignal to the display section 71 to display a captured image.

The recording section 69 causes the recording medium 70 including anonvolatile memory, for example, to record (store) image data or thelike captured by the imaging element 65. Further, the recording section69 performs control to read out the image data from the recording medium70. The recording medium 70 may be attachable and detachable.

The display section 71 includes a panel-type display unit such as aliquid crystal panel or an organic EL display, and displays an image(video image or still image) supplied from the image signal processingsection 68. The display section 71 is mounted on a rear surface oppositeto a front surface on which the mount section 61 is disposed, and candisplay a through image or an image recorded in the recording medium 70,for example.

The power supply control section 76 supplies power supplied from thepower supply section 75, to the sections of the imaging device (body)50. In addition, the power supply control section 76 calculates a poweramount of power that can be supplied to the interchangeable lens 20while taking the operation state of the imaging device (body) 50 intoconsideration, and supplies power to the interchangeable lens 20 via themount section 61. For example, the power supply section 75 includes, forexample, a secondary battery such as a NiCd battery, a NiMH battery, ora Li battery, an AC adaptor, or the like.

The operation section 78 includes hardware keys such as a shutterbutton, a mode dial, and a zoom button, and software keys on a touchpanel layered on the display section 71, receives a predeterminedoperation performed by the user, and supplies an operation signalthereof to the body-side control section 62. The user can set aphotographing mode or set a camera parameter, for example, by operatingthe operation section 78.

As described above, the focus control section 80 receives an input ofphase difference detection pixel information (AF detection signal) forperforming auto focus (AF) processing via the imaging element 65 and theAD conversion section 66.

The focus control section 80 analyzes the inputted AF detection signal,and calculates the defocus amount (DF) which is necessary for auto focus(AF) processing.

Specifically, the deviation amount (defocus amount (DF)) between thein-focus distance and the subject distance is calculated throughanalysis of the inputted AF detection signal so that a target focus lensposition (Tgt_fc), which is a lens position for obtaining an in-focusstate of the focus lens 26 on the interchangeable lens 20 side, isdecided.

Note that, in an embodiment which will be explained below, the imagingsystem 10 depicted in FIG. 2 is assumed to perform auto focus (AF)processing using a phase difference detection scheme.

In the AF processing using the phase difference detection scheme, lighthaving passed through a lens is pupil-split to generate a pair ofimages, and the focus position (in-focus position) is detected throughanalysis of the phase difference between the pair of images generated.

Note that, as described above, detection of a focus position (in-focusposition) by the phase difference detection scheme, is disclosed in PTL1 (Japanese Patent Laid-open No. 2014-137468) and the like, for example.

Also in the imaging system according to the present disclosure,processing using a defocus amount calculated by the phase differencedetection scheme is performed.

Note that the processing according to the present disclosure is notlimited to the phase difference detection scheme, and is applicable to aconfiguration using other auto focus processing.

The focus control section 80 calculates the focus deviation amount(defocus amount) of an object (focus target) to be focused, on the basisof the AF detection signal inputted via the imaging element 65 and theAD conversion section 66, that is, a phase difference detection pixeloutput value, and calculates a target position (Tgt_fc) of the focuslens 26 necessary for focusing, on the basis of the calculated defocusamount.

The calculated target position (Tgt_fc) of the focus lens 26 isoutputted to the interchangeable lens 20 via the body-side controlsection 62 and the mount section 61.

The interchangeable lens 20 drives the focus lens 26 through processingat the lens-side control section 22 and the focus lens driving section34 in accordance with the inputted target position (Tgt_fc), and therebyperforms processing for focusing on a subject.

Note that, in focus control processing (focus processing) according tothe present disclosure, which will be explained below, the processing isperformed by use of various types of data indicating positions ordistances.

These terms will be explained.

(a) Subject distance: A subject distance refers to an actual distancefrom an imaging device to a subject to be photographed, or an actualdistance such as 2 m, 3 m, . . . , or 7 m, for example, and is alsoreferred to as an in-focus distance.

(b) In-focus position: An in-focus position refers to a lens positionwithin a lens movement frame (lens driving stroke) that obtains focusingon a subject, unlike the in-focus distance (=subject distance) describedabove. For example, the in-focus position is expressed by coordinatesbased on a reference point as an original point set within the lensmovement frame (lens driving stroke), or by a separation distance (mm)from the original point. Note that the lens movement frame refers to aregion in which the lens can move and which is formed in theinterchangeable lens.

(c) Focus lens position: A focus lens position refers to the position ofthe focus lens within the lens movement frame (lens driving stroke).Similarly to the in-focus position, the focus lens position is expressedby coordinates based on a reference point as an original point setwithin the lens movement frame (lens driving stroke), or by a separationdistance (mm) from the original point.

(d) Zoom lens position: A zoom lens position refers to the position ofthe zoom lens within the lens movement frame (lens driving stroke).Similarly to the in-focus position, the zoom lens position is expressedby coordinates based on a reference point as an original point setwithin the lens movement frame (lens driving stroke), or by a separationdistance (mm) from the original point.

(e) Target focus lens position: A target focus lens position (Tgt_fc)refers to information indicating the “(a) subject distance” forobtaining an in-focus state, or the “(c) focus lens position” forfocusing on a subject.

Note that, in one example of the processing according to the presentdisclosure, the target focus lens position is decided by use of a camcurve, and is used as a focus lens movement control command value to beoutputted from the imaging device (body) 50 to the interchangeable lens10.

(f) Subject distance information: Subject distance information is ageneric term for information that can be applied for focusingprocessing, and is at least the aforementioned (a) subject distanceand/or position information such as the (c) focus lens position and the(d) zoom lens position in the in-focus position. The (e) target focuslens position described above is also included in the subject distanceinformation.

2. Specific Sequence Example of Auto Focus (AF) Processing

Next, a specific sequence example of auto focus (AF) processing will beexplained.

FIG. 4 is a diagram depicting one example of a data output sequence ofthe imaging element 65 of the imaging device (body) 50 side in theimaging system 10 having been explained with reference to FIG. 2 .

As explained above with reference to FIG. 2 , the following two datastreams are separately outputted from the imaging element 65:

(First stream) Output of pixel information (image signal) byphotographing image pixels (RGB pixels); and

(Second stream) Output of phase difference detection pixel information((AF) detection signal) by the phase difference detection pixels 81.

FIG. 4 depicts an example of two signal processing sequences:

(A) process sequence for the first stream (photographing image signal);and

(B) process sequence for the second stream (detection signal).

Note that the (A) process sequence for the first stream (photographingimage signal) depicted in the upper stage in FIG. 4 is a processsequence example in a case where consecutive shooting of still images iscarried out.

Still images V1, V2, and V3 in FIG. 4 are obtained by consecutiveshooting.

High-speed and high-precision auto focus (AF) processing is required inconsecutive shooting.

In the top stage in FIG. 4 , synchronization signals (ta1, . . . ) forcontrolling the timings of various processes in the imaging device(body) 50 are depicted.

In the example depicted in FIG. 4 , the synchronization signals aregiven at a 16.7-ms (=( 1/60) sec) interval. The synchronization signalsare provided from the body-side control section 62 to the processingsections, for example, and each serve as a trigger for a timing toperform processing at each of the processing sections.

First, the (A) process sequence for the first stream (photographingimage signal) in FIG. 4 will be explained.

The (A) process sequence for first stream (photographing image signal)in FIG. 4 includes two processes:

(a1) exposure of photographing pixels and AD conversion; and

(a2) reading out photographing pixels (frame memory (FM) storage).

The (a1) exposure of photographing pixels and AD conversion refer toexposure in the imaging element 65 and AD conversion in the ADconversion section 66.

FIG. 4 depicts a consecutive shooting example, and depicts a sequence ina case where still images (V1, V2, V3, . . . ) are taken at a (1/20)-sec interval.

As depicted in (a1), exposure of the first image V1 in the consecutiveshooting is started in the imaging element 65 at time ta2, the exposureis performed for a predetermined period of time, the exposure result isoutputted from the imaging element 65 to the AD conversion section 66,and then, AD conversion is performed on the exposure result.

Note that the right-downward parallelogram shapes mean that the outputfrom the imaging element 65 to the AD conversion section 66 and the ADconversion are sequentially performed on the pixels constituting theimaging element 65, downwardly from an upper pixel to a lower pixel.

When exposure and AD conversion on one image such as the image V1 arecompleted, storage from the AD conversion section 66 into the framememory 67 is performed.

This process is the (a2) reading out photographing pixels (frame memory(FM) storage) depicted in FIG. 4 .

The triangular region of the image V1 depicted in (a2) of FIG. 4 meansthat data is transferred and stored from the AD conversion section 66into the frame memory 67 pixel by pixel, and thus, certain time isrequired until the storage is completed. In the depicted example,storage of the image V1 into a frame memory is started immediatelybefore time ta3, and is completed at time ta5.

Next, the (B) process sequence for the second stream (detection signal)depicted in the lower stage in FIG. 4 will be explained.

The (B) process sequence for the second stream (detection signal)depicted in the lower stage in FIG. 4 concerns pixel signals of thephase difference detection signals 81 formed in the imaging element 65.

In the (B) process sequence for the second stream (detection signal)depicted in FIG. 4 , four processes:

(b1) exposure of phase difference detection pixels and AD conversion;

(b2) reading out phase difference pixels;

(b3) calculation of a defocus amount; and

(b4) lens driving are depicted.

The (b1) exposure of phase difference detection pixels and AD conversionrefer to exposure of the phase difference detection pixels in theimaging element 65 and AD conversion in the AD conversion section 66.

The exposure of the phase difference detection pixels and AD conversionin the AD conversion section 66 are performed independently of the (1)process for the first stream (photographing image signal) depicted inthe upper stage in FIG. 4 .

In the depicted example, exposure of phase difference detection pixelsis performed at a ( 1/60)-sec interval.

Each Ph in the drawing indicates exposure of phase difference detectionpixels and AD conversion which are performed at a ( 1/60)-sec interval.

After the exposure of phase difference detection pixels depicted in (b1)of FIG. 4 , a pixel value of the difference detection pixels having beenconverted to digital data, is outputted from the AD conversion section66 to the focus control section 80.

The processes depicted in FIG. 4 :

(b2) reading out phase difference pixels; and

(b3) calculation of a defocus amount, are performed on the digital databy the focus control section 80.

In FIG. 4 , each process is indicated by a triangular shape or arectangular shape.

The exposure result of phase difference detection pixels is inputted tothe AD conversion section 66, is converted to a digital signal, and isthen inputted from the AD conversion section 66 to the focus controlsection 80.

In the configuration depicted in FIG. 2 , the focus control section 80sequentially receives, from the AD conversion section 66, an input of anAD-converted phase difference detection pixel value, in the order fromthat of an upper pixel to that of a lower pixel.

This process corresponds to the (b2) reading out phase differencepixels.

Note that FIG. 2 depicts a configuration in which an output from the ADconversion section 66 is directly inputted to the focus control section80, but a configuration in which a memory is disposed between the focuscontrol section 80 and the AD conversion section 66 such that an outputfrom the AD conversion section 66 is stored in the memory, and is theninputted to the focus control section 80 via the memory, may be adopted.

As described above, the focus control section 80 analyzes the phasedifference between a pair of images generated by phase differencedetection pixels, and thereby calculates the focus deviation amount(defocus amount (DF)) to a subject (focus target) which is a target tobe focused.

This process corresponds to the (b3) calculation of a defocus amountdepicted in FIG. 4 .

As seen from FIG. 4 , the exposure of the phase difference detectionpixels is performed at a ( 1/60)-sec interval, and the calculation of adefocus amount (DF) by the focus control section 80 is also performed ata ( 1/60)-sec interval.

The defocus amount (DF) calculated by the focus control section 80corresponds to the difference between

the target focus lens position (Tgt-fc) which corresponds to an in-focusposition for a subject, and

the current focus lens position (Cur_fc) which corresponds to thecurrent position of the focus lens.

The body-side control section 62 of the imaging device (body) 50outputs, to the interchangeable lens 20, either information regardingthe defocus amount (DF) calculated by the focus control section 80, orinformation regarding the target focus lens position (Tgt-fc) obtainedfrom the defocus amount (DF).

On the basis of either the information regarding the defocus amount (DF)or the information regarding the target focus lens position (Tgt-fc)inputted from the imaging device (body) 50, the lens-side controlsection 22 of the interchangeable lens 20 causes the focus lens drivingsection 34 to perform lens driving to drive the focus lens 26 to thetarget focus lens position (Tgt-fc).

This process corresponds to the (b4) lens driving depicted in FIG. 4 .

The (B) process sequence for the second stream (detection signal) inFIG. 4 includes the following processes:

(b1) exposure of phase difference detection pixels and AD conversion;

(b2) reading out phase difference pixels;

(b3) calculation of a defocus amount; and

(b4) lens driving.

These four processes are performed every ( 1/60) sec which is equal tothe interval of exposure of phase difference detection pixels.

3. Problems Caused when AF Processing is Performed with Focus Lens beingDriven

Next, problems caused when AF processing is performed with a focus lensbeing driven, will be explained.

In order to perform auto focus (AF) processing at high speed, it iseffective to perform the processing while driving a focus lens withoutstopping the focus lens.

However, when such processing is performed, proper processing cannot beperformed in some cases.

Specifically, it is unclear at which position the focus lens is locatedwhen phase difference detection pixel information (AF detection signal),which is adopted as a parameter for calculating a defocus amount (DF) tobe calculated by the focus control section 80, is obtained. This causesa problem that high-precision auto focus (AF) is difficult.

Hereinafter, this problem will be explained.

An example of calculating the defocus amount (DF) on the basis of thephase difference detection pixel information (AF detection signal)outputted from the imaging element 65, will be explained with referenceto FIGS. 5 and 6 .

FIG. 5 depicts an example of calculating the defocus amount (DF) on thebasis of the difference detection pixel information (AF detectionsignal) outputted from the imaging element 65 in a state where drivingof a focus lens is stopped.

On the other hand, FIG. 6 depicts an example of calculating the defocusamount (DF) on the basis of the difference detection pixel information(AF detection signal) outputted from the imaging element 65 while afocus lens is being driven.

Note that, in both the examples, the processing is performed under acondition that a subject does not move.

First, the example of calculating the defocus amount (DF) on the basisof the difference detection pixel information (AF detection signal)outputted from the imaging element 65 in a state where driving of thefocus lens is stopped, will be explained with reference to FIG. 5 .

In FIG. 5 , two diagrams:

(1) defocus amount calculation sequence; and

(2) transition of a defocus amount, are depicted in association witheach other along a time axis.

As indicated by a time axis (T) in (1) of FIG. 5 , time elapses fromleft to right.

The diagram of the (1) defocus amount calculation sequence in FIG. 5 isobtained by enlarging a part of the (B) process sequence for the secondstream (detection signal) in FIG. 4 , which has been explained abovewith reference to FIG. 4 . Similarly to (B) in FIG. 4 , three processes:

(b1) exposure of phase difference detection pixels and AD conversion;

(b2) reading out phase difference pixels; and

(b3) calculation of a defocus amount, are depicted.

In (1) of FIG. 5 ,

as the (b1) exposure of phase difference detection pixels and ADconversion,

two processes Ph1 and Ph2 which are performed at a ( 1/60)-sec interval,are depicted.

The first exposure of phase difference detection pixels and ADconversion, which are denoted by Ph1, are started at time t1. Theexposure is completed at time t2, the AD conversion is performed at timet2, and then, the AD conversion is completed at time t3. After time t3,the focus control section 80 performs

(b2) reading out phase difference pixels, and

(b3) calculation of a defocus amount.

At time t4, the “(b3) calculation of a defocus amount” is completed bythe focus control section 80.

On the other hand, the lower stage in FIG. 5 depicts

(2) transition of a defocus amount.

The time axis therefor is in accordance with the time axis depicted in(1) of FIG. 5 .

In (2) of FIG. 5 , the following lines:

(c) a focus lens in-focus position, that is, a target focus lensposition (Tgt_fc); and

-   -   (d) the current focus lens position, that is, a current focus        lens position (Cur_fc),        are depicted along the time axis.

The vertical direction in (2) of FIG. 5 indicates the movable directionof the focus lens. Focus adjustment is performed by upwardly/downwardlymoving the focus lens.

Auto focus (AF) processing, that is, focusing processing is accomplishedby moving the current focus lens position (Cur_fc) to the target focuslens position (Tgt_fc).

FIG. 5 depicts a process example of calculating the defocus amount (DF)on the basis of the phase difference detection pixel information (AFdetection signal) outputted from the imaging element 65 in the statewhere driving of the focus lens is stopped.

Therefore, the (d) current focus lens position, that is, the currentfocus lens position (Cur_fc), indicated in the (2) transition of defocusin FIG. 5 is fixed without varying with the elapse of time.

At start time t1 of the first exposure of phase difference detectionpixels and AD conversion denoted by Ph1 in the (1) defocus amountcalculation sequence on the upper stage in FIG. 5 , the defocus amountis df1.

Note that the defocus amount is the difference between the target focuslens position (Tgt_fc) and the current focus lens position (Cur_fc).

Also, at time t3 when the AD conversion denoted by Ph1 in (1) of FIG. 5is completed, the defocus amount is df3.

In FIG. 5 , a defocus amount df2 at one certain time between time t1 totime t3 is also depicted.

During any of these times, the current focus lens position, that is, thecurrent focus lens position (Cur_fc), does not change. Under thecondition that a subject does not move, the defocus amount does notchange during the period of time t1 to time t3.

In other words, an expression:

df1=df2=df3

is established.

Thus, when the focus lens is stopped during the exposure time period ofthe phase difference detection pixels, the defocus amount is constant.Also for the defocus amount (DF) calculated by the focus control section80 on the basis of the exposure result of the phase difference detectionpixels, an expression:

DF=df1=df2=df3

is established.

In other words, the defocus amount (DF) calculated by the focus controlsection 80 on the basis of the exposure result of phase differencedetection pixels is a precise defocus amount (DF) that is equal to thedifference between the target focus lens position (Tgt_fc) and thecurrent focus lens position (Cur_fc). By use of this defocus amount(DF), the focus lens is moved toward the target focus lens position(Tgt_fc) so that focusing processing, that is, proper auto focus (AF)processing can be performed.

Next, an example of calculating the defocus amount (DF) on the basis ofthe phase difference detection pixel information (AF detection signal)outputted from the imaging element 65 while driving the focus lens, willbe explained with reference to FIG. 6 .

Similarly to FIG. 5 , FIG. 6 depicts two diagrams:

(1) defocus amount calculation sequence; and

(2) transition of a defocus amount, in association with each other alonga time axis.

As indicated by a time axis (T) in (1) of FIG. 6 , time elapses fromleft to right.

As in FIG. 5 , the diagram of the (1) defocus amount calculationsequence in FIG. 6 depicts three processes:

(b1) exposure of phase difference detection pixels and AD conversion;

(b2) reading out phase difference pixels; and

(b3) calculation of a defocus amount.

The process timings of the three processes are identical to those in (1)of FIG. 5 explained above.

The first exposure of phase difference detection pixels and ADconversion, which are denoted by Ph1, are started at time t1. Theexposure is completed at time t2, the AD conversion is performed at timet2, and then, the AD conversion is completed at time t3. After time t3,the focus control section 80 performs

(b2) reading out phase difference pixels, and

(b3) calculation of a defocus amount.

At time t4, the “(b3) calculation of a defocus amount” is completed bythe focus control section 80.

The lower stage in FIG. 6 depicts

(2) transition of a defocus amount.

The time axis therefor is in accordance with the time axis depicted in(1) of FIG. 6 .

In (2) of FIG. 6 , the following lines are depicted along the time axis:

(c) a focus lens in-focus position, that is, a target focus lensposition (Tgt_fc); and

(d) the current focus lens position, that is, a current focus lensposition (Cur_fc), as in (2) of FIG. 5 .

The vertical direction in (2) of FIG. 6 indicates the movable directionof the focus lens. Focus adjustment is performed by upwardly/downwardlymoving the focus lens.

FIG. 6 depicts a process example of calculating the defocus amount (DF)on the basis of the phase difference detection pixel information (AFdetection signal) outputted from the imaging element 65 while drivingthe focus lens. When such processing is performed, higher-speed AFprocessing (focusing processing) can be expected.

Therefore, the (d) current focus lens position, that is, the currentfocus lens position (Cur_fc), depicted in (2) transition of a defocusamount of FIG. 6 changes with the elapse of time. In the example in FIG.6 , the current focus lens position (Cur_fc) changes toward the targetfocus lens position (Tgt_fc) with the elapse of time. This is caused bymoving the focus lens toward the in-focus position on the basis of thephase difference detection result of phase difference detection pixels(Ph0), which is obtained prior to the Ph1 depicted in (1) of FIG. 6 ,for example.

As described above, when the defocus amount (DF) is calculated on thebasis of the phase difference detection pixel information (AF detectionsignal) outputted from the imaging element 65 with the focus lens beingdriven, the current focus lens position (Cur_fc) sequentially changes.As a result of this, the actual defocus amount also changessequentially.

At start time t1 of the first exposure of phase difference detectionpixels and AD conversion denoted by Ph1 in the (1) defocus amountcalculation sequence on the upper stage in FIG. 6 , the defocus amountis df1.

Also, at time t3 when the AD conversion denoted by Ph1 depicted in (1)of FIG. 6 is completed, the defocus amount is df3.

In FIG. 6 , a defocus amount df2 at one certain time between time t1 totime t3 is also depicted.

The current focus lens positions (Cur_fc) at these times are differentfrom one another. The defocus amount also changes during the period oftime t1 to time t3.

In other words, an expression:

df1=df2=df3

is not established, and thus, an expression

df1≠df2≠df3 is established.

Even under this condition, at time t3 depicted in (1) of FIG. 6 , thefocus control section 80 calculates one defocus amount (DF) on the basisof the result of the exposure of the phase difference detection pixels(Ph1).

The one defocus amount (DF) calculated by the focus control section 80is obtained in accordance with one set of phase difference informationcalculated on the basis of the result of the exposure of the phasedifference detection pixels (Ph1).

In auto focus (AF) processing, the target focus lens position (Tgt_fc)which is a focus lens position for focusing on a subject needs to becalculated by use of the one defocus amount (DF) calculated by the focuscontrol section 80.

A relational expression:

DF=(Tgt−fc)−(Cur_fc)

is established between the defocus amount DF, the target focus lensposition (Tgt_fc), and the current focus lens position (Cur_fc).

Therefore, in order to calculate the target focus lens position(Tgt_fc), the current focus lens position (Cur_fc), which is theposition of the focus lens at a point of time when one set of phasedifference information used for calculation of the defocus amount DFcalculated by the focus control section 80 is obtained, needs to beestimated.

One example of estimating the position of the focus lens at a point oftime when phase difference information is calculated, will be explainedwith reference to FIG. 7 .

As explained above with reference to FIG. 6 , FIG. 7 depicts twodiagrams:

(1) defocus amount calculation sequence; and

(2) transition of a defocus amount,

in association with each other along a time axis.

Similarly to FIG. 6 , FIG. 7 depicts a process example of calculatingthe defocus amount (DF) on the basis of the phase difference detectionpixel information (AF detection signal) outputted from the imagingelement 65 while driving the focus lens, and the (d) current focus lensposition (Cur_fc) depicted in the (2) transition of a defocus amount inFIG. 7 changes toward the target focus lens position (Tgt_fc) with theelapse of time.

This trajectory is identical to that in FIG. 6 .

The focus control section 80 executes steps S1 to S3 depicted in thecenter of FIG. 7 . In other words, the focus control section 80 executesthe following steps S1 to S3:

(S1) calculate a defocus amount (DF);

(S2) calculate a focus lens reference position (Ref_fc); and

(S3) calculate a target focus lens position (Tgt_fc),

Tgt_fc=Ref_fc+DF.

In calculating the defocus amount (DF) in step S1, one defocus amount(DF), which is calculated on the basis of the result of the exposure ofthe phase difference detection pixels (Ph1), is calculated.

In calculating the focus lens reference position (Ref_fc) in step S2,the position of the focus lens at a point of time when the phasedifference information is calculated, is estimated.

As depicted in FIG. 7 , the focus control section 80 performs thefollowing position estimation.

Information regarding the position of the focus lens during the periodof time when the exposure of the phase difference detection pixels isperformed to obtain the result of the exposure of the phase differencedetection pixels (Ph1), is continuously acquired. Sampling is performedat an interval of 4 msec or shorter, for example.

The focus lens reference position (Ref_fc) is calculated on the basis ofthe position information (fcn to fcm) obtained by sampling.

The focus lens reference position (Ref_fc) is calculated from theaverage value, the median value, the weighted average, or the like ofthe sampling position information (fcn to fcm), for example.

In the aforementioned manner, calculation of the focus lens referenceposition (Ref_fc) in step S2 described above is performed.

Finally, in step S3, a position for setting the focus lens to focus on asubject, that is, the target focus lens position (Tgt_fc), is calculatedby the following expression:

Tgt_fc=Ref_fc+DF.

As a result of execution of the above processes, one target focus lensposition (Tgt_fc) is decided on the basis of the result of one-timeexposure of the phase difference detection pixels (Ph1) even in thestate where the focus lens is being driven, so that auto focus (AF)processing can be performed.

However, the aforementioned processes can be applied in a case whereauto focus (AF) processing is performed with only the focus lens beingdriven.

For example, in a camera having such a lens as a varifocal lens having aconfiguration requiring focus adjustment in association with zoomadjustment, what is generally called zoom tracking for performing focusadjustment at time of zooming needs to be performed.

For example, when a user (photographing person) performs zoom adjustmentto change a zoom position, a subject distance for focusing changes as aresult of the zoom setting.

Therefore, in auto focus (AF) processing in a case where the zoomposition is changed, proper focusing cannot be achieved unless the zoomposition is taken into consideration.

An example of performing zoom setting in zoom tracking and setting afocus lens position, will be explained with reference to FIG. 8 .

A curve depicted in FIG. 8 is called a cam curve.

The cam curve represents data on the correspondence between a zoom lensposition and a focus lens position indicating an in-focus positioncorresponding to various subject distances.

In the graph depicted in FIG. 8 , the horizontal axis represents a zoomlens position (Wide side to Tele side), and the vertical axis representsa focus lens position (imaging element side to subject side), and thus,the position of the zoom lens and the position of the focus lens in eachof in-focus positions corresponding to a plurality of subject distances(26 m, 8 m, 10 m, 15 m, 20 m, and infinity (inf)) are depicted.

For example, in a case where the subject distance is 10 m, when the zoomlens position=zm1, the focus lens position for focusing on a subject isfc1.

However, in the case where the subject distance is also 10 m, when thezoom position is changed and the zoom lens position=zm2, the focus lensposition for focusing on a subject is changed to fc2.

In this manner, when the user (photographing person) changes theposition of the zoom lens, the in-focus state is not maintained.Accordingly, a defocused state is generated unless the focus lens ismoved.

Therefore, in auto focus (AF) processing involving a change of the zoomposition, proper processing cannot be performed unless the zoom positionis taken into consideration.

[4. Auto Focus (AF) Processing in which Zoom Position is Taken intoConsideration]

Next, a configuration in which proper auto focus (AF) processing can beperformed even in a case where a zoom position is changed, that is, azoom lens position is changed, will be explained.

As depicted in FIG. 9 , in the imaging system 10 according to thepresent disclosure, the memory 42 of the interchangeable lens 20 and thememory 72 of the imaging device (body) 50 each store cam curve datahaving been explained with reference to FIG. 8 .

In other words, data on the cam curve representing the correspondencebetween the zoom lens position and the focus lens position in anin-focus position at each subject distance, is held.

The cam curve represents data indicating the correspondence between thezoom lens position and the focus lens position in the imaging system 10.

In the imaging system 10 according to the present disclosure, auto focus(AF) processing is performed by referring to the cam curves stored inthe memory 42 of the interchangeable lens 20 and the memory 72 of theimaging device (body) 50.

When the processing is performed by referring to the cam curves,high-precision auto focus (AF) processing can be achieved even in thecase where zooming is performed

Note that, in a case where either one of the interchangeable lens 20 orthe imaging device (body) 50 holds the cam curve data, the device (theinterchangeable lens 20 or the imaging device (body) 50) holding the camcurve may be configured to provide the cam curve data to the otherdevice not holding the cam curve data.

In auto focus (AF) processing which is performed in the imaging system10 according to the present disclosure, the interchangeable lens 20regularly acquires the focus lens position and the zoom lens position,and outputs the focus lens position and the zoom lens position to theimaging device (body) 50.

As explained above with reference to FIG. 7 , acquisition of the lensposition information is performed multiple times at an interval of 4msec or shorter, or the like, for example, during a period of one-timeexposure of the phase difference detection pixels.

The lens position information acquired by the interchangeable lens 20 issequentially, or as data obtained by compiling values obtained bymultiple times of measurement, outputted to the imaging device (body)50.

By using the position information regarding the focus lens and the zoomlens, pixel information regarding the phase difference detection pixels,and the cam curve, the imaging device (body) 50 calculates the in-focusposition of the focus lens in which the zoom position has been takeninto consideration, that is, the target focus lens position (Tgt_fc).

A specific process sequence thereof will be explained with reference toFIG. 10 and later.

FIG. 10 is an explanatory diagram of the overall sequence of auto focus(AF) processing which is executed by the imaging system 10 according tothe present disclosure and in which the zoom position is taken intoconsideration.

FIG. 10 depicts only components which are mainly used for auto focus(AF) processing, among the components of the interchangeable lens 20 andthe imaging device (body) 50 in the imaging system 10 explained abovewith reference to FIG. 2 .

Note that the same cam curve corresponding to the imaging system 10 isstored in each of the memory 42 of the interchangeable lens 20 and thememory 72 of the imaging device (body) 50.

In FIG. 10 , steps S01 to S05 are depicted as a process procedure(sequence) of auto focus processing.

First, the overall flow of auto focus processing which is performed inthe imaging system according to the present disclosure will be explainedwith reference to FIG. 10 . Thereafter, the details of the steps will beexplained with reference to FIG. 11 and later.

Steps S01 to S05 depicted in FIG. 10 will be explained.

(Step S01)

In step S01, the lens position (state) detection section 27 of theinterchangeable lens 20 detects lens position information, that is, afocus lens position and a zoom lens position, and transmits the detectedlens position information from the interchangeable lens 20 side to thefocus control section 80 of the imaging device (body) 50.

Note that data exchange between the interchangeable lens 20 and theimaging device (body) 50, which is omitted in FIG. 10 , is performed viathe lens-side control section 22 and the mount section 21 of theinterchangeable lens 20 and the body-side control section 62 and themount section 61 of the imaging device (body) 50.

The lens position (state) detection section 27 of the interchangeablelens 20 performs acquisition of the focus lens position and the zoomlens position at a fixed interval of 4 msec or shorter, for example.

In other words, as explained above with reference to FIG. 7 ,acquisition of the lens positions is performed at least two or moretimes during the period of the one-time exposure of the phase differencedetection pixels.

The lens position information acquired by the lens position (state)detection section 27 of the interchangeable lens 20 is sequentially, oras data obtained by compiling values obtained by multiple times ofmeasurement, outputted to the imaging device (body) 50.

(Step S02)

In step S02, the phase difference detection pixel information, which isthe result of the exposure of the phase difference detection pixelsobtained by the imaging element 65 of the imaging device (body) 50, isinputted to the focus control section 80, and the defocus amount (DF) iscalculated by the focus control section 80.

As explained above with reference to FIG. 7 , the exposure of the phasedifference detection pixels is performed at a ( 1/60)-sec interval, forexample. Therefore, the phase difference detection pixel information isinputted to the focus control section 80 at the ( 1/60)-sec interval.

By using the phase difference detection pixel information, the focuscontrol section 80 calculates the defocus amount (DF).

(Step S03)

Step S03 is executed by the focus control section 80 of the imagingdevice (body) 50.

The focus control section 80

receives an input of the position information regarding the focus lensand the zoom lens from the interchangeable lens 20, in step S01, and

receives an input of pixel information regarding the phase differencedetection pixels from the imaging element 65, in step S02.

By using the inputted information, and

the cam curve stored in the memory 72, the focus control section 80calculates the in-focus position of the focus lens in which the zoomposition is taken into consideration, that is, the target focus lensposition (Tgt_fc).

Note that the target focus lens position (Tgt_fc) is the subjectdistance information indicating the subject distance for focusing, orthe lens position for focusing on a subject.

Note that the calculation of the target focus lens position (Tgt_fc) bythe focus control section 80 is performed at the phase differencedetection pixel information input interval (i.e., at a ( 1/60)-secinterval, in the present embodiment).

A specific example of calculation of the target focus lens position(Tgt_fc) by the focus control section 80 will be explained later.

(Step S04)

In step S04, the target focus lens position (Tgt_fc) calculated by thefocus control section 80 of the imaging device (body) 50 is transmittedfrom the body-side control section 62 of the imaging device (body) 50 tothe lens-side control section 22 of the interchangeable lens 20.

(Step S05)

Step S05 is executed by the lens-side control section 22 and the focuslens driving section 34 of the interchangeable lens 20.

By using

the target focus lens position (Tgt_fc) inputted from the imaging device(body) 50,

the current zoom lens position (zm_now), and

the cam curve stored in the memory 42, the lens-side control section 22and the focus lens driving section 34 of the interchangeable lens 20newly calculate the latest target focus lens position (Tgt_fc_now), anddrive the focus lens 26 toward the latest target focus lens position(Tgt_fc_now).

The outline of the overall flow of the auto focus processing which isexecuted in the imaging system according to the present disclosure hasbeen explained above with reference to FIG. 10 .

Next, the details of the steps will be explained with reference to FIG.11 and later.

(Step S01)

First, step S01 will be explained in detail with reference to FIG. 11 .

As explained with reference to FIG. 10 , in step S01, the lens position(state) detection section 27 of the interchangeable lens 20 detects thelens position information, that is, the focus lens position and the zoomlens position, and transmits the detected lens position information fromthe interchangeable lens 20 side to the focus control section 80 of theimaging device (body) 50.

FIG. 11 depicts the following two diagrams on the upper and lowerstages, respectively:

(1) imaging device (body)-side processing; and

(2) interchangeable lens-side processing.

The two types of processing are depicted in time series.

The time axis is depicted on the upper portion of the (1) imaging device(body)-side processing in the upper stage. Time elapses from left toright.

The (1) imaging device (body)-side processing on the upper stage in FIG.11 depicts the following processes in time series:

(1 a) exposure of phase difference detection pixels and AD conversion;

(1 b) reading out phase difference detection pixels; and

(1 c) calculation of a defocus amount (DF) and calculation of a targetfocus lens position (Tgt_fc).

The above processes respectively correspond to:

(b1) exposure of phase difference detection pixels and AD conversion;

(b2) reading out phase difference detection pixels; and

(b3) calculation of a defocus amount, which are depicted in the (1)defocus amount calculation sequence in FIGS. 5 to 7 having beenexplained above.

However, (1 c) in FIG. 11 includes calculation of a target focus lensposition (Tgt_fc), in addition to calculation of the defocus amount(DF).

This process will be explained later.

In (1) of FIG. 11 , one-time exposure of the phase difference detectionpixels and AD conversion (Ph1), which are performed during a time periodfrom time t1 to time t2, are depicted as the “(1 a) exposure of phasedifference detection pixels and AD conversion”.

In (1 a) of FIG. 11 , Ph1 denotes a process similar to that of the (b1)exposure of phase difference detection pixels and AD conversion in the(1) defocus amount calculation sequence having been explained above withreference to FIGS. 5 to 7 , and denotes the exposure of the phasedifference detection pixels and the AD conversion which are performed ata ( 1/60) sec-interval (=16.7 msec-interval).

On the other hand, the (2) interchangeable lens-side processing on thelower stage in FIG. 11 depicts the following processes in time series:

(2 a) acquisition of the zoom lens position; and

(2 b) acquisition of the focus lens position.

In the (2) interchangeable lens-side processing on the lower stage inFIG. 11 , zm0, zm1, zm2, . . . each denote zoom lens positioninformation which is regularly acquired (sampled) by the lens position(state) detection section 27 of the interchangeable lens 20.

Also, fc0, fc1, fc2, . . . each denote focus lens position informationwhich is regularly acquired by the lens position (state) detectionsection 27 of the interchangeable lens 20.

The lens position (state) detection section 27 of the interchangeablelens 20 performs acquisition of the focus lens position and the zoomlens position at a fixed interval.

Note that, in this embodiment, the lens position (state) detectionsection 27 performs acquisition of the focus lens position (fcn) and thezoom lens position (zmn) at an interval of 4 msec or shorter, forexample.

The lens position acquisition interval can be set variously. However,acquisition of the lens positions is performed at least two or moretimes during the period of the one-time exposure of the phase differencedetection pixels.

The lens position information acquired by the lens position (state)detection section 27 of the interchangeable lens 20 is sequentially oras data obtained by compiling multiple-times acquisition values,outputted to the imaging device (body) 50.

In the example depicted in FIG. 11 , a plurality of focus lens positions(fcn) and a plurality of zoom lens positions (zmn) acquired during apredetermined period of time (approximately, 10 msec) by the lensposition (state) detection section 27 are grouped, and are outputted tothe imaging device (body) 50 by groups (Gp1, Gp2, . . . ).

This process corresponds to step S01 depicted in FIG. 11 .

The lens position (state) detection section 27 outputs, to the imagingdevice (body) 50, a plurality of focus lens positions (fcn) and aplurality of zoom lens positions (zmn) acquired during the predeterminedperiod of time (approximately, 10 msec) in association with lensposition acquisition time (sampling time) information regarding thecorresponding lens positions.

Note that, as the time information, absolute time information suppliedfrom a clock in the lens-side control section 22 is used, for example.

FIG. 12 depicts an example of the lens position information which isoutputted from the interchangeable lens 20 to the imaging device (body)50.

In FIG. 12 , an example of a series of data which is outputted from theinterchangeable lens 20 to the imaging device (body) 50 is depicted.

The data is outputted from the interchangeable lens 20 to the imagingdevice (body) 50 by groups, that is, by a group 1 (Gp1) and a group 2(Gp2) depicted in FIG. 12 .

Data of the group 1 (Gp1) is configured by four lens position data setsacquired at the predetermined interval of 4 msec or shorter, forexample, during a time period of time ts0 msec to ts3 msec indicatingthe lens position sampling times, that is, the following data sets:

time=ts0msec: lens positions (zm0, fc0);

time=ts1msec: lens positions (zm1, fc1);

time=ts2 msec: lens positions (zm2, fc2); and

time=ts3 msec: lens positions (zm3, fc3).

These data sets are collectively outputted from the interchangeable lens20 to the imaging device (body) 50.

Note that an abstract expression is used here for the data such as zm0and fc0, but the position data actually indicates a specific lensposition.

These data sets are stored in the memory 72 of the imaging device (body)50, and are used in step S03 which is executed by the focus controlsection 80 of the imaging device (body) 50, that is, calculation of thetarget focus lens position (Tgt_fc).

(Step S02)

Next, the details of step S02 will be explained with reference to FIG.13 .

As explained above with reference to FIG. 10 , in step S02, phasedifference detection pixel information which is the result of theexposure of the phase difference detection pixels in the imaging element65 of the imaging device (body) 50 is inputted to the focus controlsection 80, and the defocus amount (DF) is calculated by the focuscontrol section 80.

FIG. 13 is similar to FIG. 11 having been explained above, and depictsthe following two diagrams on the upper and lower stages:

(1) imaging device (body)-side processing; and

(2) interchangeable lens-side processing.

These two types of processing are depicted in time series.

Step S02 is [DF] of the “(1 c) calculation of a defocus amount (DF) andcalculation of a target focus lens position (Tgt_fc)” in the (1) imagingdevice (body)-side processing of FIG. 13 .

The process sequence of the (1) imaging device (body)-side processing inFIG. 13 is as follows.

During a period from time t1 to t2, the (1 a) exposure of phasedifference detection pixels and the AD conversion are performed.

This process is performed by the imaging element 65 and the ADconversion section 66 of the imaging device (body) 50.

During the following period from time t2 to t3, the (1 b) reading outphase difference detection pixels is performed.

In this process, the focus control section 80 of the imaging device(body) 50 sequentially reads out the phase difference detection pixelinformation (pixel values) having undergone AD conversion, from the ADconversion section 66.

After time t3, step S02, that is, calculation of the defocus amount(DF), is performed.

The exposure of the phase difference detection pixels is performed at a( 1/60)-sec interval, for example. Therefore, the phase differencedetection pixel information is inputted to the focus control section 80at a ( 1/60)-sec interval.

By using the phase difference detection pixel information, the focuscontrol section 80 calculates a defocus amount (DF) at the ( 1/60)-secinterval.

Calculation of the defocus amount is performed in the same manner as aconventional one.

In other words, the focus control section 80 analyzes the phasedifference between a pair of images from the phase difference detectionpixel information, and calculates the focus deviation amount (defocusamount (DF)) from an object to be focused (focus target).

In one example, the calculated defocus amount (DF) is defined by

DF=−0.48 m.

This defocus amount (DF) corresponds to the deviation amount between thesubject distance and the in-focus distance of the “current focus lensposition”.

However, the calculated defocus amount (DF) has the problem explainedabove with reference to FIG. 7 . In other words, it is unclear where theaforementioned “current focus lens position” is.

The defocus amount (DF) calculated by the focus control section 80 isone value obtained from the period from time t1 to t2 depicted in the (1a) exposure of phase difference detection pixels and AD conversion ofthe (1) imaging device (body)-side processing in FIG. 13 , that is, theresult of the exposure of the phase difference detection pixels and theAD conversion. However, the lens position sequentially changes becausethe focus lens and the zoom lens also move during the period from timet1 to t2.

Therefore, there is a problem that the calculated defocus amount (DF) ismerely information corresponding to the position of the focus lens at acertain point of time between time t1 and t2.

(Step S03)

Next, step S03 will be explained with reference to FIG. 14 and later.

As described above with reference to FIG. 10 , step S03 is executed bythe focus control section 80 of the imaging device (body) 50.

The focus control section 80

receives an input of position information regarding the focus lens andthe zoom lens from the interchangeable lens 20, in step S01, and

receives an input of pixel information regarding phase differencedetection pixels from the imaging element 65, in step S02.

By using

the inputted information, and

the cam curve stored in the memory 72,

the focus control section 80 calculates the in-focus position of thefocus lens in which the zoom position has been taken into consideration,that is, the target focus lens position (Tgt_fc).

Step S03, which is depicted at the right end of the “(1 c) calculationof a defocus amount (DF) and calculation of a target focus lens position(Tgt_fc)” of the (1) imaging device (body)-side processing in FIG. 14 ,is calculation of the target focus lens position (Tgt_fc) that isperformed by the focus control section 80.

The focus control section 80 calculates the target focus lens position(Tgt_fc) by the following procedures:

(procedure 1) calculation of a focus lens reference position (Ref_fc);and

(procedure 2) calculation of a target focus lens position (Tgt_fc) byusing focus lens reference position (Ref_fc) and the defocus amount (DF)calculated at step S02, in accordance with an expression

Tgt_fc=Ref_fc+DF.

Note that the target focus lens position (Tgt_fc) is subject distanceinformation indicating a subject distance for focusing or a lensposition for focusing on a subject.

Hereinafter, these procedures will be explained in detail.

First, (procedure 1) calculation of a focus lens reference position(Ref_fc) will be explained.

By using focus lens positions (fcn) and zoom lens positions (zmn)obtained during a time period from start time (t1) of exposure of phasedifference detection pixels used for calculation of the defocus amount(DF) in step S02 to start time (t3) of calculation of the defocus amount(DF) in step S02, the focus control section 80 of the imaging device(body) 50 calculates the focus lens reference position (Ref_fc) of thistime period.

Lens position information during the period from the start time (t1) ofthe exposure of the phase difference detection pixels to the start time(t3) of the calculation of the defocus amount (DF) is reference positioncalculation data depicted in the (2) interchangeable lens-sideprocessing in FIG. 14 . In other words, the lens position informationincluding six pairs (zm0, fc0) to (zm5, fc5) including

focus lens position information: fc0 to fc5, and

zoom lens position information: zm0 to zm5, is set as reference positioncalculation data, and the reference position calculation data (zm0, fc0)to (zm5, fc5) is developed on the cam curve, whereby the focus lensreference position (Ref_fc) is calculated.

FIG. 15 depicts data similar to that having been explained above withreference to FIG. 12 , and depicts lens position information which istransmitted from the lens position (state) detection section 27 of theinterchangeable lens 20 to the imaging device (body) 50 side.

This information is stored in the memory 72 of the imaging device (body)50.

The focus control section 80 of the imaging device (body) 50 selects andacquires reference position calculation data from the lens positioninformation, which is depicted in FIG. 15 and is stored in the memory 72of the imaging device (body) 50.

In other words, the reference position calculation data is lens positioninformation including

focus lens position information: fc0 to fc5, and

zoom lens position information: zm0 to zm5, which is obtained during thetime period from the start time (t1) of the exposure of the phasedifference detection pixels to the start time (t3) of the calculation ofthe defocus amount (DF) in step S02.

The focus control section 80 sets the six pairs (zm0, fc0) to (zm5, fc5)of the lens position information as reference position calculation data,develops the reference position calculation data (zm0, fc0) to (zm5,fc5) on the cam curve, and thereby calculates the focus lens referenceposition (Ref_fc).

The focus control section 80 acquires the cam curve stored in the memory72, that is, cam curve data indicating the correspondence between thezoom lens position and the focus lens position in an in-focus positionat each subject distance, and develops the aforementioned referenceposition calculation data on the cam curve.

This process will be explained with reference to FIG. 16 .

FIG. 16 depicts a cam curve acquired from the memory 72 by the focuscontrol section 80.

The focus control section 80 detects, from the cam curve, pointscorresponding to the reference position calculation data (zm0, fc0) to(zm5, fc5).

As depicted in FIG. 16 , the points corresponding to the referenceposition calculation data (zm0, fc0) to (zm5, fc5) are decided on thecam curve.

For example, from the cam curve, it can be found that the zoom lensposition=zm0 and the focus lens position=fc0 included in the referenceposition calculation data (zm0, fc0) are a zoom lens position and afocus lens position for focusing on a subject at a subject distance=20m.

Also for the remaining reference position calculation data (zm1, fc2) to(zm5, fc5), the following information can similarly be obtained from thecam curve.

The reference position calculation data (zm1, fc1) corresponds to a lensposition (the zoom lens position and the focus lens position) forfocusing on a subject at a subject distance=15 m.

The reference position calculation data (zm2, fc2) corresponds to a lensposition (the zoom lens position and the focus lens position) forfocusing on a subject at a subject distance=10 m.

The reference position calculation data (zm3, fc3) corresponds to a lensposition (the zoom lens position and the focus lens position) forfocusing on a subject at a subject distance=10 m.

The reference position calculation data (zm4, fc4) corresponds to a lensposition (the zoom lens position and the focus lens position) forfocusing on a subject at a subject distance=8 m.

The reference position calculation data (zm5, fc5) corresponds to a lensposition (the zoom lens position and the focus lens position) forfocusing on a subject at a subject distance=5 m.

By using the detection result of points, on the cam curve, correspondingto the reference position calculation data (zm0, fc0) to (zm5, fc5), thefocus control section 80 calculates the focus lens reference position(Ref_fc).

FIG. 17 depicts a specific example of calculation of a focus lensreference position (Ref_fc).

From the detection result of points, on the cam curve, corresponding tothe reference position calculation data (zm0, fc0) to (zm5, fc5)depicted in FIG. 17 , the focus control section 80 acquires, on the camcurve, information regarding a subject distance when each of the focuslens positions (fc0 to fc5) is in an in-focus position. In the presentexample, as explained above with reference to FIG. 16 , the in-focusposition (=subject distance for focusing) is as follows:

fc0=20 m,

fc1=15 m,

fc2=10 m,

fc3=10 m,

fc4=8 m, and

fc5=8 m.

The focus control section 80 calculates the average value (ave) of theabove data as the focus lens reference position (Ref_fc). In otherwords, the focus control section 80 calculates the focus lens referenceposition (Ref_fc) by the following expression:

Ref_fc=ave (20 m, 15 m, 15 m, 10 m, 10 m, 8 m, 8 m)=11.8 m.

The calculated value 11.8 m is set as the focus lens reference position(Ref_fc) during the time period from the start time (t1) of the exposureof the phase difference detection pixels to the start time (t3) ofcalculation of the defocus amount (DF) in step S02 in FIG. 14 .

Note that the calculated focus lens reference position (Ref_fc) is not avalue directly representing the focus lens position in theinterchangeable lens 20, but a value obtained by converting the focuslens position to a subject distance.

The focus control section 80 calculates, as the focus lens referenceposition (Ref_fc), the distance (distance from the camera) of a subjectto be focused.

The above example has a configuration in which the focus lens referenceposition (Ref_fc) is calculated from the points, on the cam curve,corresponding to the reference position calculation data (fcn to fcm)which is the sampling position information, that is, from the averagevalue (ave) of the subject distance at an in-focus position.

However, this calculation is one example. The focus lens referenceposition (Ref_fc) may be calculated not only from the points, on the camcurve, corresponding to the reference position calculation data (fcn tofcm), that is, the average value (ave) of the subject distance at anin-focus position, but also from the points, on the cam curve,corresponding to the reference position calculation data (fcn to fcm),that is, the median value, the weighted average, or the like of thesubject distance at an in-focus position, for example.

Next, by using

the calculated focus lens reference position (Ref_fc)=11.8 m, and

the defocus amount (DF)=−4.8 m calculated in step S02,

the focus control section 80 calculates the target focus lens position(Tgt_fc) for obtaining an in-focus state of the focus lens.

As depicted in FIG. 17 , the focus control section 80 calculates thetarget focus lens position (Tgt_fc) in accordance with the followingexpression:

$\begin{matrix}{{Tgt\_ fc} = {({Ref\_ fc}) + \left( {DF} \right)}} \\{= {11.8 - {4.8}}} \\{= {7m}}\end{matrix}.$

Note that the target focus lens position (Tgt_fc)=7 m calculated by theabove expression is not a value directly representing the focus lensposition in the interchangeable lens 20, but a value obtained byconverting the focus lens position to a subject distance.

The focus control section 80 calculates, as the target focus lensposition (Tgt_fc), a distance (distance from the camera) to a subject tobe focused.

As depicted in FIG. 17 , the focus control section 80 calculates thetarget focus lens position (Tgt_fc) by computation of the focus lensreference position (Ref_fc) and the defocus amount (DF).

As a result of this, the target focus lens position (Tgt_fc) is 7 m. Inother words, a focus lens position, at which a subject at the subjectdistance=7 m can be focused, is calculated as the target focus lensposition (Tgt_fc).

(Step S04)

Next, step S04 will be explained with reference to FIG. 18 .

As described above with reference to FIG. 10 , in step S04, the targetfocus lens position (Tgt_fc) calculated by the focus control section 80of the imaging device (body) 50 is transmitted from the body-sidecontrol section 62 of the imaging device (body) 50 to the lens-sidecontrol section 22 of the interchangeable lens 20.

In FIG. 18 , this process is denoted by step S04. The target focus lensposition (Tgt_fc) calculated by the focus control section 80 of theimaging device (body) 50 is transmitted to the lens-side control section22 of the interchangeable lens 20 via the body-side control section 62of the imaging device (body) 50.

(Step S05)

Next, step S05 will be explained with reference to FIG. 19 .

As explained above with reference to FIG. 10 , step S05 is executed bythe lens-side control section 22 and the focus lens driving section 34of the interchangeable lens 20.

As depicted in step S05 in FIG. 19 , the lens-side control section 22 ofthe interchangeable lens 20 receives an input of the target focus lensposition (Tgt_fc) from the imaging device (body) 50, and then, acquiresthe latest zoom lens position (zm_now) at present.

This information is acquired from the lens position (state) detectionsection 27 of the interchangeable lens 20.

Next, the lens-side control section 22 detects, from the cam curveacquired from the memory 42,

the corresponding position between the target focus lens position(Tgt_fc)=7 m inputted from the imaging device (body) 50 and the currentzoom lens position (zm_now), and

newly calculates the latest target focus lens position (Tgt_fc_now) inaccordance with the detected position.

This process will be explained with reference to FIG. 20 .

In FIG. 20 , a line indicating the target focus lens position (Tgt_fc)=7m inputted from the imaging device (body) 50 is a thick line.

This line of 7 m indicates the target focus lens position (Tgt_fc)=7 minputted from the imaging device (body) 50. This indicates a subjectdistance for obtaining an in-focus state of the focus lens that islocated at the already calculated focus lens reference position(Ref_fc).

The lens-side control section 22 detects, on the line of 7 m, a positioncorresponding to the current zoom lens position (zm_now).

The detected position is the position (zm_now) depicted in FIG. 20 .

The focus lens position corresponding to the position (zm_now) is set asthe latest target focus lens position (Tgt_fc_now).

The target focus lens position (Tgt_fc)=7 m calculated in step S03 bythe focus control section 80 on the imaging device (body) 50 sidecorresponds to a distance to a subject to be focused, calculated on thebasis of the focus lens reference position (Ref_fc)=11.8 m and thedefocus amount (DF)=−4.8 m.

However, thereafter, the zoom position is further changed to be set atthe position (zm_now) depicted in FIG. 20 .

At the latest zoom position (zm_now), the focus lens position forfocusing on the subject at the subject distance=7 m is the latest targetfocus lens position (Tgt_fc_now) which is obtained in accordance withthe cam curve depicted in FIG. 20 .

As described so far, the lens-side control section 22

newly calculates the latest target focus lens position (Tgt_fc_now) fromthe cam curve by using the target focus lens position (Tgt_fc)=7 minputted from the imaging device (body) 50 and the current zoom lensposition (zm_now).

The lens-side control section 22 causes the focus lens driving section34 to drive the focus lens 26 to the latest target focus lens position(Tgt_fc_now).

As a result of this process, auto focus (AF) processing of driving thefocus lens position to the in-focus position while reflecting the latestzoom position, can be performed.

Note that, in the aforementioned example of steps S03 to S05, the focuscontrol section 80 of the imaging device (body) 50 transmits the subjectdistance (7 m) as the target focus lens position (Tgt_fc) to thelens-side control section 22 of the interchangeable lens 20.

This is one example. The target focus lens position (Tgt_fc) which istransmitted from the focus control section 80 of the imaging device(body) 50 to the lens-side control section 22 of the interchangeablelens 20 is not limited to the subject distance (7 m), and may be anydata as long as the focus lens position for focusing on a subject can bedecided from the data, and any other data may be used.

Specifically, for example, coordinate information (focus lens position,zoom lens position) regarding one point corresponding to the subjectdistance=7 m on the cam curve may be transmitted, as the target focuslens position (Tgt_fc), from the focus control section 80 of the imagingdevice (body) 50 to the lens-side control section 22 of theinterchangeable lens 20.

In other words, the last zoom position (zm5) acquired during theexposure time period and the coordinate information (zm5, fcX)indicating the focus lens position (fcX) on the cam curve correspondingto this zoom position are transmitted, as the target focus lens position(Tgt_fc), by the focus control section 80 of the imaging device (body)50 to the lens-side control section 22 of the interchangeable lens 20.

The lens-side control section 22 of the interchangeable lens 20 receivesthe coordinate information, and recognizes, by referring to the camcurve, that the coordinate position (zm5, fcX) is disposed at a pointcorresponding to the subject distance=7 m on the cam curve. Further, thefocus lens position corresponding to the latest zoom position iscalculated. The focus lens is driven by use of this calculated value asa command value.

For example, a configuration of performing the above processing may beadopted.

Thus, it is sufficient that the target focus lens position (Tgt_fc)which is transmitted from the imaging device (body) 50 to theinterchangeable lens 20 is data with which a focus lens position forfocusing on a subject can be decided, that is, subject distanceinformation.

Note that, as explained above, the subject distance information is ageneric term for information that can be applied for focusingprocessing, and represents at least a subject distance position orposition information regarding a focus lens position and a zoom lensposition in an in-focus position.

In steps S03 to S05, the subject distance information is transmittedfrom the imaging device (body) 50 to the interchangeable lens 20,whereby auto focus (AF) processing in which the latest zoom position isreflected is performed.

5. Data Communication Between Interchangeable Lens and Imaging Device(body), and Process Sequence Thereof

Next, data communication which is performed between the interchangeablelens 20 and the imaging device (body) 50 in the aforementioned autofocus (AF) processing, and the process sequence thereof will beexplained with reference to sequence diagrams depicted in FIGS. 21 and22 .

FIGS. 21 and 22 each depict a sequence diagram of data communicationbetween the interchangeable lens 20 and the imaging device (body) 50,and the process sequence thereof.

Steps S01 to S05 depicted in FIGS. 21 and 22 correspond to steps S01 toS05 explained above with reference to FIG. 10 and FIGS. 11 to 20 .

Hereinafter, these steps will be explained sequentially.

(Step S01)

Step S01 is transmission of lens position information (zmn, fcn) fromthe interchangeable lens 20 to the imaging device (body) 50.

This process has been explained above with reference to FIGS. 11 and 12. In this process, the lens position (state) detection section 27 of theinterchangeable lens 20 regularly detects lens position information,that is, a focus lens position and a zoom lens position, and thedetected lens position information is transmitted together withinformation regarding the acquisition time of the position information,from the interchangeable lens 20 side to the focus control section 80 ofthe imaging device (body) 50.

For example, the lens position (state) detection section 27 performsacquisition of the focus lens position (fcn) and the zoom lens position(zmn) at an interval of 4 msec or shorter, for example, and transmits,sequentially or as data obtained by compiling values obtained bymultiple times of measurement, the acquired positions to the imagingdevice (body) 50.

The data explained above with reference to FIG. 12 is an example of thedata which is transmitted from the interchangeable lens 20 to theimaging device (body) 50. As depicted in FIG. 12 , data on thecorrespondence between the lens position information (zmn, fcn) andacquisition time (sampling time) information regarding the lens positioninformation (zmn, fcn) is transmitted from the interchangeable lens 20to the imaging device (body) 50. The transmitted data is stored in thememory 72 of the imaging device (body) 50.

(Steps S02 a and S02 b)

Steps S02 a and S02 b in FIG. 21 are depicted by dividing step S02explained above with reference to FIG. 13 .

As explained above with reference to FIGS. 10 and 13 , in step S02,pixel information regarding the phase difference detection pixels in theimaging element 65 of the imaging device (body) 50 is inputted to thefocus control section 80, and the defocus amount (DF) is calculated bythe focus control section 80.

Step S02 a in FIG. 21 represents exposure of the phase differencedetection pixels in the imaging element 65 of the imaging device (body)50 by use of light inputted via the interchangeable lens 20.

Step S02 b is executed by the focus control section 80 of the imagingdevice (body) 50 on the basis of the result of the exposure in step S02a.

The focus control section 80 receives an input of pixel informationregarding the phase difference detection pixels in the imaging element65, and calculates the defocus amount (DF).

Exposure of the phase difference detection pixels is performed at a (1/60)-sec interval, for example, and the phase difference detectionpixel information is inputted to the focus control section 80 at the (1/60)-sec interval. By using the phase difference detection pixelinformation, the focus control section 80 calculates the defocus amount(DF) at the ( 1/60)-sec interval.

However, as explained above, only one value is calculated as the defocusamount (DF) in accordance with one-time exposure of the phase differencedetection pixels. Thus, in the case where the focus lens or the zoomlens is moving during the exposure time period (t1 to t2) of phasedifference detection pixels, there is a problem that it is unclear atwhich point of time during the period from time t1 to t2, the positionof the focus lens to which the calculated defocus amount (DF)corresponds is obtained.

(Steps S03 a and 03 b)

Steps S03 a and 03 b in FIGS. 21 and 22 are depicted by dividing stepS03 explained above with reference to FIGS. 14 to 17 .

As explained above with reference to FIG. 10 and FIGS. 14 to 17 , stepS03 is calculation of the target focus lens position (Tgt_fc) which isperformed by the focus control section 80 of the imaging device (body)50.

Step S03 a in FIG. 21 is

(1) calculation of a focus lens reference position (Ref_fc) having beenexplained with reference to FIGS. 14 to 17 .

Step S03 b in FIG. 22 is

(2) calculation of a target focus lens position (Tgt_fc) having beenexplained with reference to FIGS. 14 to 17 .

First, in step S03 a, the focus control section 80 of the imaging device(body) 50 calculates the focus lens reference position (Ref_fc).

As explained above with reference to FIG. 14 , the focus lens positions(fcn) and the zoom lens positions (zmn) obtained during the time periodfrom the start time of the exposure of the phase difference detectionpixels used for the calculation of the defocus amount (DF) in step S02 bto the start time of the calculation of the defocus amount (DF), areused in this process.

For example, reference position calculation data depicted in the (2)interchangeable lens-side processing in FIG. 14 is used, for example.The reference position calculation data (zm0, fc0) to (zm5, fc5) isdeveloped on the cam curve, whereby the focus lens reference position(Ref_fc) is calculated.

The focus control section 80 calculates the focus lens referenceposition (Ref_fc) by developing the reference position calculation data(zm0, fc0) to (zm5, fc5) on the cam curve.

This process is the process having been explained above with referenceto FIG. 16 .

The focus control section 80 detects, from the cam curve, pointscorresponding to the reference position calculation data (zm0, fc0) to(zm5, fc5), as depicted in FIG. 16 .

The focus control section 80 calculates the focus lens referenceposition (Ref_fc) by using the points, on the cam curve, correspondingto the reference position calculation data (zm0, fc0) to (zm5, fc5).

Specifically, as explained above with reference to FIG. 17 , the focuslens reference position (Ref_fc) is calculated by use of the points, onthe cam curve, corresponding to the focus lens positions (fc0 to fc5)constituting the reference position calculation data (zm0, fc0) to (zm5,fc5), that is, subject distance information for obtaining an in-focusposition.

The focus control section 80 calculates, as the focus lens referenceposition (Ref_fc), the average value (ave) of the points, on the camcurve, corresponding to the focus lens positions (fc0 to fc5)constituting the reference position calculation data, that is, thesubject distance for obtaining an in-focus position, for example.

Note that, the focus lens reference position (Ref_fc) calculated here isnot a value directly indicating the focus lens position in theinterchangeable lens 20, but is a value obtained by converting the focuslens position into a subject distance.

The focus control section 80 calculates, as the focus lens referenceposition (Ref_fc), the distance (distance from the camera) to a subjectdistance to be focused.

As explained above, the focus lens reference position (Ref_fc) may beset not only from the points, on the cam curve, corresponding to thereference position calculation data (fcn to fcm), that is, the averagevalue (ave) of the subject distance for obtaining an in-focus position,but also from the points, on the cam curve, corresponding to thereference position calculation data (fcn to fcm), that is, theintermediate value, the weighted average, or the like of the subjectdistance for obtaining an in-focus position, for example.

Next, step S03 b depicted in FIG. 22 , that is, calculation of thetarget focus lens position (Tgt_fc), will be explained.

The focus control section 80 calculates the target focus lens position(Tgt_fc) for obtaining an in-focus state of the focus lens, by using

the reference focus lens position (Ref_fc) calculated in step S03 a, and

the defocus amount (DF) calculated in the previous step S02 b.

As explained above with reference to FIG. 17 , the focus control section80 calculates the target focus lens position (Tgt_fc) in accordance withthe following expression:

Tgt_fc=(Ref_fc)+(DF).

Note that the target focus lens position (Tgt_fc) calculated by theabove expression is not a value directly indicating the focus lensposition in the interchangeable lens 20, but a value obtained byconverting the focus lens position to a subject distance.

(Step S04)

In step S04 depicted in FIG. 22 , the target focus lens position(Tgt_fc) calculated by the focus control section 80 of the imagingdevice (body) 50 is transmitted from the body-side control section 62 ofthe imaging device (body) 50 to the lens-side control section 22 of theinterchangeable lens 20.

This process has been explained above with reference to FIG. 18 .

(Steps S05 a and S05 b)

Steps S05 a and 05 b in FIG. 22 are depicted by dividing the process instep S05 having been explained above with reference to FIGS. 19 and 20 .

As explained above with reference to FIGS. 19 and 20 , step S05 isexecuted by the lens-side control section 22 and the focus lens drivingsection 34 of the interchangeable lens 20, and is for driving the focuslens to focus on a subject.

First, the lens-side control section 22 of the interchangeable lens 20receives an input of the target focus lens position (Tgt_fc) from theimaging device (body) 50, and then, acquires the latest zoom lensposition (zm_now) at present.

This information is acquired from the lens position (state) detectionsection 27 of the interchangeable lens 20.

Next, the lens-side control section 22 detects, from the cam curveacquired from the memory 42, corresponding positions between the targetfocus lens position (Tgt_fc) inputted from the imaging device (body) 50and the current zoom lens position (zm_now), and newly calculates thelatest target focus lens position (Tgt_fc_now) in accordance with thedetected positions.

This process is the process having been explained above with referenceto FIG. 20 .

Next, in step S05 b in FIG. 22 , the lens-side control section 22 causesthe focus lens driving section 34 to drive the focus lens 26 to thelatest target focus lens position (Tgt_fc_now).

By this process, auto focus (AF) processing in which the focus lensposition is driven to the in-focus position while the latest zoomposition is reflected, can be performed.

Note that, as explained above, the target focus lens position (Tgt_fc)which is transmitted from the imaging device (body) 50 to theinterchangeable lens 20 in steps S03 to S05 described above is notlimited to data on a subject distance itself, and may be data with whichthe focus lens position for focusing on a subject can be decided, thatis, the subject distance information.

Note that, as explained above, the subject distance information is ageneric term for information that can be applied for focusingprocessing, and represents at least a subject distance position orposition information regarding a focus lens position and a zoom lensposition in an in-focus position.

In steps S03 to S05 described above, the subject distance information istransmitted from the imaging device (body) 50 to the interchangeablelens 20, whereby auto focus (AF) processing in which the latest zoomposition is reflected is performed.

6. Conclusion of Configuration According to Present Disclosure

An embodiment according to the present disclosure have been explained indetail with reference to specific embodiments. However, it is obviousthat a person skilled in the art can make any modification oralternative within the scope of the gist of the present disclosure. Inother words, the present disclosure has been disclosed byexemplification, and should not be interpreted in a limited manner. Inorder to determine the gist of the present disclosure, the claims shouldbe taken into consideration.

Note that the technique disclosed herein may also have the followingconfigurations.

(1) An interchangeable lens device including

a memory that stores a cam curve representing a relationship between aposition of a zoom lens and a position of a focus lens according to asubject distance, and

a control section that performs focus control by driving the focus lens,wherein

the control section

-   -   transmits zoom lens position information indicating the position        of the zoom lens and focus lens position information indicating        the position of the focus lens to an imaging device, and    -   performs the focus control on the basis of subject distance        information indicating a substance distance which is calculated        by the imaging device with use of the zoom lens position        information and the focus lens position information acquired        from the control section, and on the basis of the cam curve.        (2) The interchangeable lens device according to (1), in which

the control section further transmits the cam curve to the imagingdevice.

(3) The interchangeable lens device according to (1) or (2), in which

the control section performs the focus control on the basis of thesubject distance information which is calculated by the imaging devicewith use of multiple sets of the zoom lens position information andmultiple sets of the focus lens position information acquired from thecontrol section at a predetermined time interval during an exposure timeperiod of a detection information acquisition pixel for use incalculation of a defocus amount, and on the basis of the cam curve.

(4) The interchangeable lens device according to any one of (1) to (3),in which

the control section

-   -   acquires a latest zoom lens position after receiving an input of        the subject distance information from the imaging device, and    -   detects, from the cam curve, a corresponding point between the        subject distance information and the latest zoom lens position,        and performs the focus control on the basis of the detected        corresponding point.        (5) The interchangeable lens device according to any one of (1)        to (4), in which

the control section acquires lens position information regarding thefocus lens and the zoom lens at least two or more times at apredetermined time interval during an exposure time period of thedetection information acquisition pixel, and outputs the lens positioninformation to the imaging device.

(6) The interchangeable lens device according to any one of (1) to (5),in which

the detection information acquisition pixel includes a phase differencedetection pixel, and

the control section acquires lens position information regarding thefocus lens and the zoom lens at a predetermined time interval during anexposure time period of the phase difference detection pixel, andoutputs the lens position information to the imaging device.

(7) The interchangeable lens device according to any one of (1) to (6),in which

the control section outputs, to the imaging device, informationconcerning a time at which lens position information regarding the focuslens and the zoom lens is acquired, in association with the lensposition information.

(8) An imaging device including

a memory that stores a cam curve representing a relationship between aposition of a zoom lens and a position of a focus lens according to asubject distance, and

a focus control section that calculates an in-focus position of thefocus lens, wherein

the focus control section

-   -   receives an input of pixel information regarding a detection        information acquisition pixel, and calculates a defocus amount,    -   receives, from a connected interchangeable lens device, an input        of multiple sets of lens position information regarding the        focus lens and the zoom lens acquired at a predetermined time        interval during an exposure time period of the detection        information acquisition pixel,    -   detects points, on the cam curve, corresponding to the multiple        sets of lens position information, and calculates a reference        focus lens position by using the detected corresponding points        on the cam curve, and    -   calculates subject distance information indicating a subject        distance, by using the calculated reference focus lens position        and the defocus amount.        (9) The imaging device according to (8), in which

the focus control section

-   -   sets, as reference position calculation data, multiple sets of        lens position information regarding the focus lens and the zoom        lens acquired during a time period from start of the exposure        time period of the detection information acquisition pixel to        start of calculation of the defocus amount, and    -   calculates the reference focus lens position by using the        reference position calculation data.        (10) The imaging device according to (8) or (9), in which

the focus control section

-   -   detects points, on the cam curve, corresponding to the multiple        sets of lens position information, and calculates, as the        reference focus lens position, an average value of multiple sets        of subject distance information constituting the detected        corresponding points on the cam curve.        (11) The imaging device according to any one of (8) to (10), in        which

the focus control section

-   -   detects points, on the cam curve, corresponding to the multiple        sets of lens position information, and calculates, as the        reference focus lens position, an intermediate value or a        weighted average value of multiple sets of subject distance        information constituting the detected corresponding points on        the cam curve.        (12) The imaging device according to any one of (8) to (10), in        which

the detection information acquisition pixel includes a phase differencedetection pixel, and

the focus control section receives an input of pixel informationregarding the phase difference detection pixel, and calculates a defocusamount.

(13) An imaging system including an interchangeable lens and an imagingdevice, in which

the interchangeable lens

-   -   acquires lens position information regarding a focus lens and a        zoom lens at a predetermined time interval during an exposure        time period of a detection information acquisition pixel for use        in calculation of a defocus amount, and outputs the lens        position information to the imaging device, and

the imaging device

-   -   receives an input of pixel information regarding the detection        information acquisition pixel, and calculates a defocus amount,    -   calculates a reference focus lens position by using the lens        position information inputted from the interchangeable lens, and    -   calculates subject distance information indicating a subject        distance, by using the calculated reference focus lens position        and the defocus amount, and outputs the subject distance        information to the interchangeable lens.        (14) The imaging system according to (13), in which

the imaging device

-   -   includes a memory that stores a cam curve representing a        relationship between a position of the zoom lens and a position        of the focus lens according to a subject distance, and    -   detects points, on the cam curve, corresponding to multiple sets        of the lens position information, and calculates a reference        focus lens position by using the detected corresponding points        on the cam curve.        (15) The imaging system according to (13) or (14), in which

the interchangeable lens

-   -   includes a memory that stores a cam curve representing a        relationship between a position of the zoom lens and a position        of the focus lens according to a subject distance,    -   acquires a latest zoom lens position after receiving an input of        the subject distance information from the imaging device, and    -   detects, from the cam curve, a corresponding point between the        subject distance information and the latest zoom lens position,        and performs the focus control on the basis of the detected        corresponding point.        (16) A focus control method which is executed by an        interchangeable lens device,

the interchangeable lens including

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a control section that performs focus control by driving the        focus lens, and

the method including, by means of the control section:

-   -   transmitting zoom lens position information indicating the        position of the zoom lens and focus lens position information        indicating the position of the focus lens to an imaging device;        and    -   performing the focus control on the basis of subject distance        information indicating a subject distance which is calculated by        the imaging device with use of the zoom lens position        information and the focus lens position information acquired        from the control section, and on the basis of the cam curve.        (17) A focus control method which is executed by an imaging        device,

the imaging device including

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a focus control section that calculates an in-focus position of        the focus lens, and

the method including, by means of the focus control section:

-   -   receiving an input of pixel information regarding a detection        information acquisition pixel, and calculating a defocus amount;    -   receiving, from a connected interchangeable lens device, an        input of multiple sets of lens position information regarding        the focus lens and the zoom lens acquired at a predetermined        time interval during an exposure time period of the detection        information acquisition pixel;    -   detecting points, on the cam curve, corresponding to the        multiple sets of lens position information, and calculating a        reference focus lens position by using the detected        corresponding points on the cam curve; and    -   calculating subject distance information indicating a subject        distance by using the calculated reference focus lens position        and the defocus amount.        (18) A program for causing an interchangeable lens device to        perform focus control processing,

the interchangeable lens including

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a control section that performs focus control by driving the        focus lens, and

the program being for causing the control section to:

-   -   transmit zoom lens position information indicating the position        of the zoom lens and focus lens position information indicating        the position of the focus lens to an imaging device; and    -   perform the focus control on the basis of subject distance        information indicating a subject distance which is calculated by        the imaging device with use of the zoom lens position        information and the focus lens position information acquired        from the control section, and on the basis of the cam curve.        (19) A program for causing an imaging device to perform focus        control processing,

the imaging device including

-   -   a memory that stores a cam curve representing a relationship        between a position of a zoom lens and a position of a focus lens        according to a subject distance, and    -   a focus control section that calculates an in-focus position of        the focus lens, and

the program being for causing the focus control section to execute:

-   -   reception of an input of pixel information regarding a detection        information acquisition pixel and calculation of a defocus        amount;    -   reception, from a connected interchangeable lens device, of an        input of multiple sets of lens position information regarding        the focus lens and the zoom lens acquired at a predetermined        time interval during an exposure time period of the detection        information acquisition pixel;    -   detection of points, on the cam curve, corresponding to the        multiple sets of lens position information, and calculation of a        reference focus lens position by using the detected        corresponding points on the cam curve; and    -   calculation of subject distance information indicating a subject        distance by using the calculated reference focus lens position        and the defocus amount.

Further, the series of processes described herein can be executed byhardware, software, or a composite structure thereof. When the processesare executed by software, a program having a process sequence thereforrecorded therein can be executed after being installed in a memoryincorporated in dedicated hardware in a computer, or can be executedafter being installed in a general-purpose computer capable of executingvarious processes. For example, such a program may previously berecorded in a recording medium. The program can be installed in thecomputer from the recording medium. Alternatively, the program can bereceived over a network such as a LAN (local area network) or theInternet, and be installed in a recording medium such as an internalhard disk.

Note that the processes described herein are not necessarily executed inthe described time-series, and the processes may be executed parallellyor separately, as needed or in accordance with the processing capacityof a device to execute the processes. Further, in the presentdescription, a system refers to a logical set structure including aplurality of devices, and the devices of the structure are notnecessarily included in the same casing.

INDUSTRIAL APPLICABILITY

With the configuration according to one embodiment of the presentdisclosure, a device and a method by which high-precision auto focus(AF) processing can be performed while a focus lens or a zoom lens isbeing operated, are implemented, as explained above.

Specifically, for example, an interchangeable lens acquires positioninformation regarding a focus lens and a zoom lens at a predeterminedtime interval during an exposure time period of detection informationacquisition pixels for use in calculation of a defocus amount (DF), andoutputs the position information to an imaging device. The imagingdevice calculates the defocus amount (DF) by using information regardingthe detection information acquisition pixels, calculates a referencefocus lens position (Ref_fc) by using points, on a cam curve,corresponding to the inputted lens position information, calculates atarget focus lens position (Tgt_fc) in an in-focus position, from thereference focus lens position (Ref_fc) and the defocus amount (DF), andoutputs the target focus lens position (Tgt_fc) to the interchangeablelens.

With this configuration, a device and a method by which high-precisionauto focus (AF) processing can be performed while a focus lens or a zoomlens is being operated, are implemented.

REFERENCE SIGNS LIST

-   1 Imaging system-   2 Interchangeable lens-   5 Imaging device (body)-   6 Imaging element-   7 Display section-   8 Operation section (shutter button)-   10 Imaging system-   20 Interchangeable lens-   21 Mount section-   22 Lens-side control section-   23 Zoom lens-   24 Hand shake correction lens-   25 Aperture-   26 Focus lens-   27 Lens position (state) detection section-   31 Zoom lens driving section-   32 Hand shake control section-   33 Aperture control section-   34 Focus lens driving section-   41 Operation section-   42 Memory-   43 Power supply control section-   50 Imaging device (body)-   61 Mount section-   62 Body-side control section-   63 Shutter-   64 Shutter control section-   65 Imaging element-   66 AD conversion section-   67 Frame memory-   68 Image signal processing section-   69 Recording section-   71 Display section-   72 Memory-   75 Power supply section-   76 Power supply control section-   78 Operation section-   80 Focus control section

1.-7. (canceled)
 8. An imaging device comprising: a memory that stores acam curve representing a relationship between a position of a zoom lensand a position of a focus lens according to a subject distance, the camcurve being transmitted from a connected interchangeable lens; and afocus control circuitry configured to receive distance information,calculate control information for controlling the focus lens based onthe cam curve and the distance information, and transmit the controlinformation to the connected interchangeable lens.
 9. The imaging deviceaccording to claim 8, wherein the focus control circuitry is furtherconfigured to set multiple sets of lens position information regardingthe focus lens and the zoom lens acquired during a time period fromstart of an exposure time period of a detection information acquisitionpixel to start of calculation of a defocus amount, and calculate anaverage value by using the multiple sets of lens position information.10. (canceled)
 11. The imaging device according to claim 8, wherein thefocus control circuitry is further configured to calculate anintermediate value or a weighted average value of multiple sets ofsubject distance information constituting points on the cam curve, andcalculate a lens position information by using the intermediate value orthe weighted average value and a defocus amount.
 12. The imaging deviceaccording to claim 8, wherein a detection information acquisition pixelincludes a phase difference detection pixel, and the focus controlcircuitry is further configured to receive an input of pixel informationregarding the phase difference detection pixel, and calculate a defocusamount based on the input of the pixel information.
 13. An imagingsystem comprising an interchangeable lens and an imaging device, whereinthe interchangeable lens including a memory storing a cam curverepresenting a relationship between a position of a zoom lens and aposition of a focus lens according to a subject distance, and theimaging device including a focus control circuitry configured to receivedistance information, calculate control information for controlling thefocus lens based on the cam curve and the distance information, andtransmit the control information to the interchangeable lens. 14.(canceled)
 15. (canceled)
 16. (canceled)
 17. A focus control methodcomprising: receiving, with focus control circuitry, distanceinformation; calculating, with the focus control circuitry, controlinformation for controlling a focus lens based on a cam curve and thedistance information, the cam curve representing a relationship betweena position of a zoom lens and a position of the focus lens according toa subject distance, the cam curve being transmitted from a connectedinterchangeable lens; and transmitting, with the focus controlcircuitry, the control information to the connected interchangeablelens.
 18. (canceled)
 19. A non-transitory computer-readable mediumcomprising instructions that, when executed by an electronic processor,causes the electronic processor to perform a set of operationscomprising: receiving distance information; calculating controlinformation for controlling a focus lens based on a cam curve and thedistance information, the cam curve representing a relationship betweena position of a zoom lens and a position of the focus lens according toa subject distance, the cam curve being transmitted from a connectedinterchangeable lens; and transmitting the control information to theconnected interchangeable lens.
 20. The non-transitory computer-readablemedium according to claim 19, wherein the set of operations furtherinclude calculating an in-focus position of the focus lens.
 21. Thefocus control method according to claim 17, further comprising:calculating, with the focus control circuitry, an in-focus position ofthe focus lens.
 22. The imaging system according to claim 13, whereinthe focus control circuitry is further configured to calculate anin-focus position of the focus lens.
 23. The imaging device according toclaim 8, wherein the focus control circuitry is further configured tocalculate an in-focus position of the focus lens.